JP4350996B2 - Organic electroluminescence device, surface light source and display device - Google Patents

Abstract

An organic electroluminescence cell including at least one organic layer and a pair of electrodes, the organic layer including a light-emitting layer and sandwiched between the pair of electrodes, the pair of electrodes includinga reflective electrode and a transparent electrode, the organic electroluminescence cell formed to satisfy the expression: Bo < B ¸ in which B 0 is a frontal luminance value of luminescence radiated from a light extraction surface to an observer, and B ¸ is a luminance value of the luminescence at an angle of from 50° to 70°, wherein a reflection/refraction angle disturbance region is provided so that the angle of reflection/refraction of the luminescence is disturbedwhile the luminescence is output from the light-emitting layer to the observer side through the transparent electrode.

Description

  The present invention relates to an organic electroluminescence device having excellent luminous efficiency, particularly, external extraction efficiency of emitted light, a highly efficient (polarized) surface light source using the organic electroluminescence device, and a (liquid crystal) display device comprising the same And about.

Electroluminescent elements and light-emitting diodes, which are provided with a light-emitting layer on the electrodes to obtain light emission, are used not only as display devices, but also for flat lighting, optical fiber light sources, liquid crystal display backlights, and liquid crystal projector backlights. Research and development is actively progressing as various light sources.
In particular, the organic electroluminescence element is excellent in terms of light emission efficiency, low voltage driving, light weight, and low cost, and has attracted attention in recent years. In these light source applications, the greatest concern is the improvement of luminous efficiency, and improvements in device configuration, materials, driving methods, manufacturing methods, etc. are being studied with the aim of luminous efficiency comparable to fluorescent lamps.

However, in an in-solid light-emitting device that extracts light from the light-emitting layer itself, such as an organic electroluminescence device, light emitted above the critical angle determined by the refractive index of the light-emitting layer and the refractive index of the output medium is totally reflected and confined inside. And lost as guided light.
In the calculation based on the classical law of refraction (Snell's law), when the refractive index of the light emitting layer is n, the light extraction efficiency η for extracting the generated light to the outside is η = 1 / (2n ² ). Approximated. If the refractive index of the light emitting layer is 1.7, η is about 17%, and 80% or more of the light is lost as guided light and lost in the side face direction of the device.

In addition, the organic electroluminescence element has only singlet excitons that contribute to light emission among the excitons generated by recombination of electrons and holes injected from the electrodes, and the generation probability is 1/4. It is. Even considering only this, the efficiency is as low as 5% or less.
In recent years, as a method for increasing the light emission efficiency of the light emitting layer itself, development of a light emitting material capable of obtaining light emission also from phosphorescence from triplet excitons (Japanese Patent Laid-Open No. 2001-313178) has been advanced, and quantum efficiency has been dramatically improved. There is also a possibility of improvement.
However, even if the quantum efficiency can be improved, the light emission efficiency is reduced by multiplying the extraction efficiency. In other words, if the extraction efficiency can be improved, there remains room for a dramatic improvement in luminous efficiency as a synergistic effect.

  In this way, in order to extract guided light to the outside, a region where the reflection / refraction angle is disturbed is formed between the light emitting layer and the exit surface, and Snell's law is broken, so that light that is originally totally reflected as guided light. It is necessary to change the transmission angle of the light or to give the light emission itself a light collecting property. However, it is not easy to form a region that emits all the guided light to the outside, and therefore, proposals have been made to extract as much guided light as possible.

  For example, as a method of improving the extraction efficiency, a method of improving the extraction efficiency by giving the substrate itself a light condensing property (Japanese Patent Laid-Open No. Sho 63-314795), or a light emitting layer formed with discotic liquid crystal A method of improving the front directivity of light itself (Japanese Patent Laid-Open No. 10-321371), a method of forming a three-dimensional structure, an inclined surface, a diffraction grating, etc. on the element itself (Japanese Patent Laid-Open Nos. 11-214162 and 11-214163) JP-A-11-283951) has been proposed. However, these proposals have problems such as a complicated configuration and a reduction in luminous efficiency of the light emitting layer itself.

Further, as a relatively simple method, a method has been proposed in which a light diffusing layer is formed and the light refraction angle is changed to reduce light in the total reflection condition.
For example, a method using a diffusion plate in which particles having a refractive index distribution structure having different refractive indexes on the inside and on the surface are dispersed in a transparent substrate (JP-A-6-347617), a single particle layer on a translucent substrate A number of methods have been proposed, such as a method using a diffusing member in which particles are arranged (Japanese Patent Laid-Open No. 2001-356207), a method of dispersing scattering particles in the same material as the light emitting layer (Japanese Patent Laid-Open No. 6-151061), and the like. These proposals have found characteristics in the characteristics of the scattering particles, the difference in refractive index from the dispersion matrix, the dispersion form of the particles, the location where the scattering layer is formed, and the like.

  By the way, in an organic electroluminescence element, by applying an electric field, a hole injected from an anode and an electron injected from a cathode are recombined to form an exciton, and a fluorescent substance (or phosphorescent substance) emits light. Is used. Therefore, in order to increase the quantum efficiency, this recombination needs to be performed efficiently. A method generally used as the method is a method in which the element is formed in a laminated structure, and examples thereof include a two-layer type of a hole transport layer / electron transport light-emitting layer, a hole transport layer / light-emitting layer / electron transport. There are three layers of layers. In order to increase efficiency, a number of stacked elements having a double hetero structure have been proposed.

In such a laminated structure, recombination occurs almost concentrated in a certain region. For example, in a two-layer type organic electroluminescence element, as shown in FIG. 12, a hole transport layer 4 and an electron sandwiched between a pair of electrodes composed of a reflective electrode 3 and a transparent electrode 2 on a support substrate 1. From the interface layer of the transporting light emitting layer 5, it is intensively generated in the region 6 on the electron transporting light emitting layer side by about 10 nm (Takuya, Ogawa et al, “IEICE TRANS ELECTRON” Vol. E85-C, No. 6, p.1239, 2002).
Further, the light generated in the light emitting region 6 is emitted in all directions. As a result, as shown in FIG. 13, there is an optical path difference between the light emitted in the light extraction surface direction on the transparent electrode 2 side and the light emitted and reflected on the reflective electrode 3 side and emitted in the light extraction surface direction.

In FIG. 13, the thickness of the electron transporting light emitting layer of the organic electroluminescence element is usually several tens to several hundreds of nanometers, which is on the order of visible light wavelength. Therefore, the light finally emitted to the outside causes interference and is strengthened or weakened depending on the distance d between the light emitting region and the reflective electrode. In FIG. 13, only the radiated light in the front direction is described, but light in the oblique direction actually exists, and the interference condition varies depending on the angle of the radiated light depending on the distance d and the emission wavelength λ. As a result, light in the front direction can be intensified and light in the wide angle direction can be intensified, or vice versa. That is, the light emission luminance varies depending on the viewing angle.
Of course, as the distance d increases, the light intensity changes significantly depending on the angle. Therefore, the film thickness is usually set so that the distance d is about 1/4 wavelength of the emission wavelength so that the light in the front direction strengthens each other.

  On the other hand, when the distance d is thinner than about 50 nm, for example, in a reflective electrode in which a metal is usually used, light absorption becomes significant, and the emission intensity is reduced and the intensity distribution is affected. That is, in the organic electroluminescence element, the radiated light distribution changes remarkably depending on the distance d between the light emitting region and the reflective electrode, and the guided light component changes greatly accordingly. Furthermore, the emission spectrum of this type of device has a broad characteristic over a relatively wide wavelength. Therefore, as a result of the wavelength range that is strengthened depending on the distance d being changed, the emission peak wavelength is changed. Also, depending on the distance d, the emission spectrum also changes depending on the viewing angle.

  In order to solve these problems, a proposal has been made to select a film thickness so as to suppress a phenomenon in which the emission color varies depending on the viewing angle (see Patent Document 1). However, there is no description regarding guided light in this proposal, and the film thickness that can suppress the viewing angle dependence of the emission color by this proposal is clearly different from the scope of the present invention described later.

For the above reason, in the classical calculation that about 80% of the emitted light is confined inside the device as guided light, the external extraction efficiency of the stacked organic electroluminescence device cannot be estimated correctly. That is, the guided light component also changes significantly depending on the element configuration. For example, M.M. H. According to a report by Lu et al. (J. Appl. Phys., Vol. 91, No. 2, p. 595, 2002), a guided light component by an element configuration is obtained by a quantum theoretical calculation method considering a microcavity effect. A detailed study of changes in
Therefore, even if a light diffusion layer or the like is formed so as to break the total reflection condition, there may be a case where a great effect as expected from classical theory cannot be obtained.

  In addition, when these organic electroluminescence elements are used as a backlight light source for a liquid crystal display device, the emitted light emitted from the elements is natural light, so that in liquid crystal display, they are converted into linearly polarized light via a polarizing plate. There is a need to. As a result, absorption loss due to the polarizing plate occurs, and there is a problem that the light use efficiency cannot be set to a value exceeding 50%. Therefore, even if the guided light is efficiently extracted by the above method, more than half of the light is absorbed by the polarizing plate.

  As a method for improving such a problem, there has been proposed a method in which an organic electroluminescence element layer is formed on an alignment film and the emitted light itself is extracted as linearly polarized light (see Patent Document 2). However, although the absorption loss in the polarizing plate can be reduced to ½ at the maximum by this proposal, there is a possibility that the luminous efficiency of the device may be lowered by inserting an alignment film for aligning the organic thin film. Further, the guided light by total reflection is not improved at all as in the conventional element.

In addition, the present applicant has proposed a method of emitting light emitted from an organic electroluminescence element through a polarization scattering film (see Patent Document 3). In this proposal, light lost as guided light due to light scattering is taken out, and outgoing light is taken out as polarized light rich in linearly polarized light, so that absorption loss in the polarizing plate can be reduced, and as a light source for a liquid crystal display device A highly efficient polarization plane light source can be provided.
However, in this proposal, for example, the relationship between the influence of interference due to the distance between the light emitting region and the reflective electrode and the relationship between guided light is not mentioned, and the effect can be maximized as a light source for a liquid crystal display device. Not a thing.

Moreover, in a liquid crystal display device, as a method for reducing absorption loss of a backlight light in a polarizing plate, a method using a polarization separation layer made of a reflective polarizer is known (see Patent Documents 4 and 5). Proposals for applying this to organic electroluminescence devices have also been made (see Patent Documents 6 and 7).
However, in organic electroluminescence devices, we studied in detail the relationship between the influence of interference due to the distance between the light emitting region and the reflective electrode and the guided light, and then combined with a reflective circular polarizer to maximize the luminous efficiency. There are no proposals that can be drawn. Accordingly, the present situation is that there is an urgent need to provide a highly efficient polarization plane light source that is optimal for liquid crystal display devices using polarized light.

Japanese Patent Laid-Open No. 5-3081 (pages 2 to 4) JP-A-11-316376 (pages 2 to 5) JP 2001-203074 (pages 2-6) JP-A-4-268505 (pages 2-6) JP-A-8-271892 (pages 2 to 5) JP 2001-244080 A (pages 2 to 4) JP 2001-31826 A (pages 2 to 3)

  In light of the circumstances as described above, the present invention provides an organic electroluminescence device that efficiently extracts loss light that has been confined as guided light inside the device, and has excellent external extraction efficiency. In addition, when used as a backlight light source of a liquid crystal display device, etc., a highly efficient organic electroluminescence element capable of efficiently extracting the above-mentioned loss light as polarized light and minimizing absorption by the polarizing plate The purpose is to provide. Furthermore, an object of the present invention is to provide a highly efficient surface light source or polarization surface light source using these organic electroluminescence elements, and a display device such as a liquid crystal display device including the same.

  As a result of intensive studies to solve the above problems, the present inventors have obtained the following knowledge. This knowledge will be described with reference to FIG. This figure shows a schematic diagram of the two-layer type organic electroluminescent element shown in FIG. 12 when the emitted light from the light emitting region 6 is emitted to the outside, only for the upper hemisphere. . Actually, there is also emitted light in the direction of the reflective electrode 3, which is omitted here.

In FIG. 9, the critical angle determined by the refractive index difference of the support substrate (glass substrate) 1 and the refractive index of the air layer is about 40 degrees. That is, light having an angle greater than 40 degrees is totally reflected at the glass / air interface and confined inside the device as guided light. On the paper, 40 degrees / 90 degrees, that is, nearly 45% of light appears to be emitted to the outside, but actual light emission is emitted in all directions. For this reason, the amount of light increases as the component becomes wider due to the solid angle. This is why the luminous efficiency is calculated to be 20% or less by classical calculation.
Further, in an actual organic electroluminescence element, a light interference effect occurs. On the other hand, the element configuration is usually determined so that the light in the front direction that can be emitted to the outside strengthens. In this case, since the guided light interferes so as to be weakened, even if a region in which the reflection / refraction angle is disturbed is formed in this element configuration, a large brightness improvement effect cannot be expected.

However, the present inventors intentionally weaken the light in the front direction and determine the device configuration so as to intensify light of a wide angle component normally confined inside the device as guided light, and most of the light quantity is distributed. When a region in which the reflection / refraction angle is disturbed is formed after amplifying the guided light, it has been found that the luminous efficiency is remarkably improved as compared with the conventional method. In other words, if there is no region where the reflection / refraction angle is disturbed, an element configuration in which the light emission efficiency is lowered and then the above region is provided is higher than when the region is provided in the conventional element configuration. It was found that an efficient organic electroluminescence device can be obtained.
Further, when the organic electroluminescence element having such a configuration is used for a backlight light source of a liquid crystal display device, the light absorbed by the polarizing plate is reduced by using a reflective polarizer. Thus, it was also found that a highly efficient polarization plane light source and a liquid crystal display device in which absorption by the polarizing plate is minimized are obtained.

  Furthermore, when the present inventors provide a region in which the reflection / refraction angle is disturbed, this region is a polarized light scattering in which minute regions having different birefringence characteristics are dispersed and distributed, particularly in the translucent resin. It has also been found that, when the active portion is provided, the guided light confined inside the device can be efficiently extracted as polarized light without using the above-described reflective polarizer. That is, in the organic electroluminescence element shown in FIG. 9, the light refraction surface side on the support substrate (glass substrate) 1, that is, the surface opposite to the transparent electrode 2, has a minute difference in birefringence characteristics in the translucent resin. A polarization-scattering portion in which the regions were distributed and distributed was formed substantially without an air layer, and the state of emission of emitted light from the light emitting region 6 at this time was examined.

  Of the emitted light, hemispherical light on the paper surface passes through the transparent electrode and the glass substrate, and enters the polarized light scattering site. In addition, the light in the lower hemisphere is reflected by the cathode and then enters the polarization-scattering portion in the same manner. Since an air layer having a low refractive index (refractive index = 1) does not intervene in this process, the emitted light can be incident on the polarized light scattering site without undergoing total reflection (however, depending on the refractive index of the transparent electrode or the glass substrate, Some light may be totally reflected). As shown in FIG. 9, in a normal element, light having an angle greater than the critical angle determined by the refractive index difference between the glass substrate and the air layer is totally reflected and lost as guided light, which is only about 20% of the normal value. Not emitted to the outside.

Most of the emitted light that has entered the polarized light scattering portion without being totally reflected is totally reflected by the difference in refractive index between the polarized light scattering portion and the air interface, and is transmitted through the polarized light scattering portion. In this transmitted light, the linearly polarized light component having a vibration surface parallel to the axial direction (Δn ₁ direction) indicating the maximum refractive index difference (Δn ₁ ) with the minute region in the polarized light scattering part is selectively and strongly scattered. A part of the angle is smaller than the total reflection angle, and is emitted to the outside (air). Incidentally, when there is no minute region and selective polarized light scattering does not occur, about 80% of the emitted light is confined due to the solid angle, and total reflection is repeated. Since the trapped light is emitted to the outside only when the total reflection condition is broken due to scattering at the interface between the minute region and the translucent resin, the efficiency of the emission is arbitrarily determined depending on the size of the minute region and the degree of existence. Can be controlled.

On the other hand, the light having the light scattered at large angles at the [Delta] n ₁ direction of scattering of the, the light satisfying the [Delta] n ₁ direction condition is not receiving scattering, the vibration directions other than further [Delta] n ₁ direction, polarized light scattering It is confined in the sex site and transmitted while repeating total reflection, and the state of polarization is canceled due to the birefringence phase difference or the like, and the opportunity to emit satisfying the above-mentioned Δn ₁ direction condition is waited for. By repeating this, linearly polarized light having a predetermined vibration surface is efficiently emitted from the polarized light scattering portion. That is, it becomes possible to take out the light originally confined as guided light as a linearly polarized light component. Therefore, according to this method, the emitted light can be efficiently emitted to the outside as polarized light rich in linearly polarized light components without forming a special light emitting means such as a microlens or a reflective dot. Further, the vibration direction of linearly polarized light can be arbitrarily changed depending on the installation angle of the polarized light scattering part. Therefore, when used for a backlight for a liquid crystal display device, power consumption can be reduced.

  In this way, light in the front direction is weakened intentionally, and the element configuration is determined so as to intensify light of a wide angle component that is normally confined inside the element as guided light, and most of the light quantity is distributed due to the solid angle It was found that when the above-mentioned polarized light scattering part is integrally formed without an air layer after amplifying light having a wide angle, the luminous efficiency can be improved as compared with the conventional method. In other words, the light emitting efficiency is lowered with a normal element, but when combined with a polarized light scattering part, the emitted light can be extracted to the outside efficiently as a linearly polarized rich light, and finally a backlight for a liquid crystal display device, etc. In the case of using for, the luminous efficiency can be dramatically improved.

In addition, the biggest drawback of organic electroluminescence elements is that the elements deteriorate due to a small amount of moisture and oxygen, and there is a problem that dark spots are generated starting from minute defects as well as a decrease in luminous efficiency. For the dark spot, see J.A. It is described in detail in a report by McElvain et al. (J. Appl. Phys. Vol. 80, No. 10, p. 6002, 1996). In order to prevent this problem, the element is usually completely sealed, but it is still not easy to completely prevent the occurrence of dark spots. This dark spot significantly reduces the appearance and visibility as a surface light source and a display device.
However, when the polarized light scattering part is formed as described above, even if some dark spots are generated, the light finally emitted to the observer side is scattered several times in the polarized light scattering part, and the external Therefore, it is possible to obtain a very good effect that the deterioration of the visibility due to the occurrence of the dark spot is hardly noticed.

The present invention has been completed based on the above findings.
That is, according to the present invention, at least one organic layer including a light-emitting layer and a pair of electrodes including an anode electrode and a cathode electrode, at least one of which is a transparent electrode, are emitted from the light extraction surface to the observer side. Is formed so that the front luminance value of the emitted light and the luminance value in the direction of 50 to 70 degrees satisfy the relationship of equation (1); front luminance value <luminance value in the direction of 50 degrees to 70 degrees. In the electroluminescence element, the region where the reflection / refraction angle of light is disturbed until the emitted light is emitted from the light emitting layer to the observer side through the transparent electrode is substantially not through the air layer. The present invention relates to an organic electroluminescence element (hereinafter simply referred to as an organic EL element).
In addition, as a particularly preferable aspect of the organic EL device having the above-described configuration, one of the anode electrode and the cathode electrode is a transparent electrode, the other is a reflective electrode, and a hole-electron recombination light-emitting region is provided. The distance between the substantially central portion of the light-emitting layer and the reflective electrode is d (nm), the peak wavelength of the fluorescence emission spectrum of the material used for the light-emitting layer is λ (nm), and the organic layer between the light-emitting layer and the reflective electrode The present invention relates to an organic EL element that satisfies the relationship of formula (2); (0.3 / n) λ <d <(0.5 / n) λ, where n is the refractive index.

Further, according to the present invention, the region in which the reflection / refraction angle of light is disturbed is composed of a light diffusing portion in which a transparent material or an opaque material having a different refractive index is dispersed and distributed in a transparent material. The organic EL element and the region where the reflection / refraction angle of light is disturbed are the lens structure, and the region where the reflection / refraction angle of light is disturbed are the uneven surface. This relates to an organic EL element having a configuration.
The present invention also relates to a surface light source comprising the organic EL elements having the above-described configurations and a display device comprising the surface light source.

The present invention also relates to an organic EL element having the above-described configuration having a reflective polarizer on the observer side from a region in which the reflection / refraction angle of light is disturbed. In particular, the reflective polarizer is a reflective circular polarizer composed of a cholesteric liquid crystal layer, and the organic EL element having the above-described configuration and the reflective polarizer are multilayered with at least two materials having different refractive indexes. The present invention relates to an organic EL element having the above configuration, which is a reflective linear polarizer. Furthermore, the present invention provides an organic EL element having the above-described configuration in which an optical compensation layer having no refractive index anisotropy in the plane and having a refractive index in the thickness direction larger than the in-plane refractive index is provided. It is concerned.
The present invention also relates to a polarization plane light source comprising the organic EL element having the above-described configuration. Furthermore, the present invention relates to a display device such as a liquid crystal display device comprising the above-described polarization plane light source.

Further, according to the present invention, the organic EL having the above-described configuration is such that a region that causes a disturbance in the reflection / refraction angle of light is composed of a polarization-scattering portion in which minute regions having different birefringence characteristics are dispersed and distributed in a translucent resin. It relates to the element. In particular, the minute region in the polarized light scattering region is composed of either a liquid crystalline material, a glass state material in which the liquid crystal phase is supercooled and fixed, or a material in which the liquid crystal phase of the polymerizable liquid crystal is cross-linked and fixed by energy rays. The organic EL element having the above-described structure and the above-described polarized light-scattering portion are formed of a liquid crystal polymer having a glass transition temperature of 50 ° C. or higher that exhibits a nematic liquid crystal phase at a temperature lower than the glass transition temperature of the resin in the translucent resin. The present invention relates to an organic EL element having the above-described structure in which regions are dispersedly contained. Further, according to the present invention, the polarized light scattering portion has a maximum refractive index difference Δn ₁ , Δn ₂ , Δn ₃ in each optical axis direction of the minute region between the minute region and the other portion. Each of the above-described configurations that is 0.03 to 0.5 (Δn ₁ ) in the axial direction (Δn ₁ direction) and 0.03 or less in two axial directions (Δn ₂ direction and Δn ₃ direction) perpendicular to the axial direction This relates to the organic EL element.
The present invention also relates to a polarization plane light source comprising the organic EL element having the above-described configuration. Furthermore, the present invention relates to a display device such as a liquid crystal display device comprising the above-described polarization plane light source.

In the present invention, the emission efficiency is low before forming the region that causes the reflection / refraction angle to be disturbed, but the region that amplifies the waveguide light component originally confined in the element and causes the reflection / refraction angle to be disturbed. By forming the structure and extracting the guided light component to the outside, the amount of emitted light can be finally increased, and a highly efficient organic EL element can be provided.
In addition, by forming a polarization scattering portion as a region that causes disturbance in the reflection / refraction angle, the amount of emitted light can be increased, and the light can be extracted as linearly polarized rich polarized light. When applied as a polarization plane light source used in a liquid crystal display device, an extremely efficient organic EL element can be provided.
In addition, by forming a light diffusing layer or lens structure as a region that causes disturbances in the reflection / refraction angle, a reflective polarizer is installed, and more than half of the guided light component is emitted as polarized light. It is possible to provide a highly efficient organic EL element when applied to a polarization plane light source used in a liquid crystal display device.
Therefore, according to the present invention, power consumption can be greatly reduced, and the current flowing through the element can be reduced, so that the life of the element can be extended. In addition, since the external extraction efficiency of the organic EL element can be improved, if the organic EL material or electrode material advances and the internal quantum efficiency improves, the luminous efficiency increases by multiplying it, and the effect of the present invention is further improved. You can get more.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows an example of a two-layer type organic EL device of the present invention. This element has a structure in which a transparent electrode 2, a hole transport layer 4, an electron transport light emitting layer 5, and a reflective electrode 3 are sequentially laminated on a support substrate 1 as a basic structure.
That is, the organic layer composed of the hole transport layer 4 and the electron transport light-emitting layer 5 is sandwiched between a pair of electrodes composed of the transparent electrode 2 and the reflective electrode 3, and is positive during operation. Recombination occurs in a region on the side of the electron transporting light emitting layer of about 10 nm from the interface layer between the hole transporting layer 4 and the electron transporting light emitting layer 5, and light emission is concentrated in the illustrated light emitting region 6.
Note that, for example, in a three-layer type organic EL element of a hole transport layer / light emitting layer / electron transport layer different from the two-layer type, when a voltage is applied between the electrodes, holes are generated from the anode and from the cathode. Electrons are injected, they move through the respective carrier transport layers and recombine in the light emitting layer to generate excitons, and EL light emission is generated as described above.

In the present invention, the basic configuration is such that, particularly, emitted light in the front direction is weakened, but guided light confined inside the device is strengthened. This will be described with reference to the characteristic diagram of FIG.
FIG. 2 shows the angular distribution of the luminance of the organic EL element having only the basic configuration described above (that is, before providing a region in which the reflection / refraction angle is disturbed, which will be described later), from 0 degrees to 80 degrees in front and 10 degrees. The characteristic diagram measured every other is shown. In the figure, curve -a is the one according to the present invention, and curve -b is the conventional one.
However, in the basic configuration, the thickness of the transparent electrode 2 is 100 nm, the thickness of the hole transport layer 4 is 50 nm, and the thickness of the electron transporting light emitting layer 5 is 140 nm (according to the present invention) and 60 nm (conventional). Stuff). Further, the current applied to the element is measured by applying a voltage so that the current of the present invention is the same as that of the conventional one.

As is apparent from FIG. 2, the conventional one has a high front luminance value, that is, a luminance value in the direction of 0 ° front, and the luminance value is substantially constant over a relatively wide angle range. Distribution is shown. On the other hand, the thing of this invention has the characteristic that a brightness | luminance becomes high, so that a front luminance value is low and it becomes a wide angle. That is, the present invention is configured to satisfy the relationship of the formula (1); the front luminance value <the luminance value in the direction of 50 degrees to 70 degrees in the angle dependency of the luminance.
This relationship is achieved in the above example due to the difference in thickness of the electron-transporting light-emitting layer 5, but the material and thickness of the organic layer including the light-emitting layer 5 and the pair of electrodes are appropriately determined. By selecting, it can be achieved arbitrarily.

In a more preferred embodiment of the present invention, the distance between the substantially central portion of the hole-electron recombination light-emitting region 6 and the reflective electrode 3 is d, and the light-emitting layer (in this case, the electron-transporting light-emitting layer 5) is used. When the peak wavelength of the fluorescence emission spectrum of the material is λ and the refractive index of the organic layer (in this case, the electron transporting light emitting layer 5) between the light emitting layer and the reflective electrode 3 is n, the formula (2) And (0.3 / n) λ <d <(0.5 / n) λ are preferably satisfied.
For example, in the above example, if the electron transporting light-emitting layer 5 is green light having a peak emission wavelength of 540 nm and its refractive index is 1.65, the distance d is 98.2 to 163.6 nm. It is desirable to be within range.

In the present invention, the basic configuration satisfying the formula (1) and preferably satisfying the formula (2) is used, and the light is reflected / refracted between the light emitting layer and the observer-side emission medium. A region 7 that causes disturbance in the corners is provided.
That is, when the light confined as guided light is incident on the region 7, its transmission angle changes, and the light whose transmission angle changes to an angle smaller than the total reflection angle is emitted to the outside of the element, and the light that is not Is also emitted outside the element while being repeatedly reflected and scattered inside the element. Thereby, the target high luminous efficiency is obtained.

In order to satisfy formula (1) or formula (2), it may be necessary to form an organic layer that is somewhat thicker than the thickness normally used for the organic layer. At that time, since the film thickness is increased, the electrical short circuit due to defects and minute unevenness of the electrode is reduced, and there is an advantage that the yield is improved, while the device resistance increases as the film thickness increases, There is a problem that the operating voltage increases. That is, even if the efficiency per unit current (cd / A) is improved, the total luminous flux amount (Im / W) per unit power may be the same as that of the prior art or may decrease depending on circumstances.
In order to avoid this, for example, a metal containing alkali metal ions, alkaline earth metal ions, rare earth metal ions, etc. as disclosed in Japanese Patent Application Laid-Open No. 2000-182774 and documents cited therein. A method of increasing the film thickness by reducing the electrical resistance of the organic layer by suppressing mixing of the organic complex compound and the organic EL material and suppressing the increase of the operating voltage may be applied. There is no particular limitation on the dopant material typified by the metal complex added to the mixed layer and its mixing method, and an appropriate method can be adopted. By such a method, the effect of the present invention can be obtained without increasing the operating voltage, so that the power efficiency can be improved as well as the current efficiency.

  Moreover, although said Formula (2) is a case where the luminescent color of an organic EL element is one color, even if it is a white element using EL light emission from several luminescent materials, such as red, green, and blue, it is this invention. The effect of is fully demonstrated. Of course, it may be a combination of white light emission by a mixed color of blue and yellow, or any light emission color other than white by color mixture. For example, in the case of a mixed color of three colors of red, green, and blue, it is impossible to satisfy the formula (2) of the present invention with all the emission colors. Therefore, for example, by applying the wavelength λ of the formula (2) to the wavelength λ of the color having the lowest luminous efficiency among the three colors, the overall luminous efficiency can be improved, and the respective emission spectra, etc. Therefore, an optimal configuration may be selected as appropriate, and the organic EL element may be manufactured so as to satisfy the formula (1). The configuration of the white element to be used is, for example, conventional techniques such as doping the host material of the light emitting layer with red, green, and blue dyes, or separating the light emitting layer into three layers of red, green, and blue, respectively. Can be done. In addition, when separating into three layers, it is also possible to satisfy Formula (2) with respect to all the luminescent colors.

Furthermore, in the present invention, it is important that the luminance value measured from the outside has an angular distribution as shown in Equation (1) before forming a region that causes a disturbance in the reflection / refraction angle. There is no problem no matter what the angular distribution of the luminance value after forming the region that causes the disturbance in the refraction angle. For example, it is preferable to have a uniform angular distribution when used for illumination that illuminates a wide range, and when used for a backlight for liquid crystal display devices used in mobile phones and mobile devices, the luminance distribution in the front direction rather than the luminance at a wide angle. Is larger. In this case, a prism sheet or the like may be installed as appropriate.
Note that when an organic EL layer is formed on a substrate in which a diffusion layer or the like is integrated in advance or a substrate that is diffusible in itself, the luminance distribution before the formation of the diffusion layer cannot be known, but under the same conditions. If an organic EL layer is formed on a normal non-diffusible substrate, it is possible to easily check whether the element is suitable for the present invention, and by observing a cross section with a transmission electron microscope, If the thickness of each layer is known, the angular distribution of luminance can be predicted to some extent.

  In the present invention, the region 7 in which the reflection / refraction angle of light is disturbed can basically efficiently disturb the transmission angle of light at an angle greater than or equal to the total reflection angle to a transmission angle less than or equal to the total reflection angle. The more the guided light confined inside the device can be emitted to the outside, the more the above effect is obtained. The region 7 needs to be formed without an air layer between the light emitting layer and the light emitting layer. This is because if air exists between the light emitting layer and the region 7, light is confined by total reflection at the interface before the emitted light enters the region 7, and the effect of the present invention cannot be expressed. .

There is no particular limitation on the method of forming the region 7 that causes the reflection / refraction angle of light to be disturbed, and a conventionally proposed method can be applied as it is.
For example, a light diffusing portion may be formed in which a transparent material or an opaque material having a different refractive index is dispersed and distributed in the transparent material. Specific examples include those in which silica particles, titania particles, zirconia particles, plastic particles, liquid crystal particles, bubbles and the like are dispersed in glass or polymer. These refractive index and refractive index difference and particle diameter of the particles are not particularly limited, but from the viewpoint of causing light scattering, the particle diameter is 0.1 to 10 μm, and the refractive index difference is 0.05. The above is preferable.

  Moreover, a lens structure can also be used suitably. A thin plate-like transparent material that changes the direction of light traveling straight by a plurality of lenses, prisms, V-grooves, etc. arranged or formed in a concentric shape, a plurality of parallel lines, a lattice shape, etc. Means. Specifically, lenticular lens sheet, Fresnel lens sheet, corner cube lens sheet, fly eye lens sheet, cat eye lens sheet, double fly eye lens sheet, double lenticular lens sheet, radial lenticular lens Examples thereof include a sheet, a prism lens film, a micro prism lens film, a lens sheet obtained by changing the convex surface of these lens sheets into a concave surface, and a transparent sphere or a semi-transparent sphere arranged in a plane. Alternatively, the direction of light may be changed by carving a groove such as a V-shaped groove. The lens sheet may be made of glass or resin.

  Furthermore, a physical uneven surface may be formed on the support substrate surface and each interface. The concavo-convex surface may be any concavo-convex structure, and includes, for example, everything from a 1 mm order structure to a 100 nm order structure. Specifically, the reactive ion etching method is applied by applying a semiconductor manufacturing process, such as matte treatment of the support substrate surface, thermal transfer of a periodic uneven structure to the organic layer (polymer layer) surface, etc. For example, a concavo-convex structure of the order of several hundred nm, that is, a photonic crystal structure can be suitably applied. The shape of the concavo-convex structure is also arbitrary, and may be a periodic structure arranged regularly or a random structure. The pitch and aspect ratio are not particularly limited, and any structure can be used as long as it can efficiently extract guided light confined inside the device.

  Also, the formation position of the region 7 that causes disturbance in the reflection / refraction angle of light is not particularly limited, and can be formed at an arbitrary position. For example, a diffusion film may be bonded to the surface of the support substrate 1 via an adhesive or an adhesive, or the support substrate 1 itself may have light diffusibility, or formed between the transparent electrode 2 and the support substrate 1. May be. When used for lighting applications with a relatively large light emitting area, it may be formed on the substrate surface, but when the light emitting area is small as in a display device, the light emitting layer and the region that causes disturbance in the reflection / refraction angle In order to reduce the parallax due to the transmission distance, it is preferable to form as close to the light emitting layer as possible.

  Next, in the present invention, as shown in FIG. 3, as shown in FIG. 3, micro-regions having different birefringence characteristics are dispersed and distributed in the translucent resin as the regions that cause disturbance in the light reflection / refraction angle. A polarized light scattering portion 70 can be formed. That is, in the same manner as the organic EL element shown in FIG. 1, the basic structure satisfying the formula (1) and preferably satisfying the formula (2) is used, and the emitted light is transferred from the electron-transporting light-emitting layer 5 to the transparent electrode 2. Here, birefringence characteristics in the above-described translucent resin are used as a region in which the reflection / refraction angle of light is disturbed on the light extraction surface side of the support substrate 1 until it is emitted to the observer side through The polarization-scattering portion 70 in which the microregions having different values are distributed and distributed is formed substantially without an air layer.

  With this configuration, light that is originally confined as guided light changes its transmission angle when it enters the polarization-scattering portion 70, and light whose transmission angle changes to an angle smaller than the total reflection angle is emitted to the outside of the device. Other light is also emitted outside the device while being repeatedly reflected and scattered within the device, and the desired high luminous efficiency can be obtained. According to this polarized light scattering portion 70, the emitted light can be emitted as polarized light rich in linearly polarized light components, and the vibration direction of the linearly polarized light can be arbitrarily changed depending on the installation angle of the polarized light scattering portion 70. When used in a backlight for a device, excellent effects such as a significant reduction in power consumption can be achieved.

In FIG. 3, the polarized light scattering portion 70 is directly formed on the support substrate 1, but may be bonded via a transparent adhesive or adhesive. At that time, it is preferable to adjust the refractive index of these pressure-sensitive adhesives and adhesives in consideration of the refractive index of each layer so that the light emitted from the organic EL element is not lost by total reflection as much as possible. For example, the refractive index of the pressure-sensitive adhesive is preferably higher than the refractive index of the support substrate 1 and smaller than the refractive index of the translucent resin of the polarized light scattering member 70. By doing so, total reflection does not occur at the support substrate / adhesive interface and the adhesive / polarized light scattering portion interface, and the emitted light can be efficiently incident on the polarized light scattering portion.
However, the refractive index of the above-mentioned pressure-sensitive adhesive or adhesive does not necessarily satisfy the above relationship. If the difference in refractive index is about 0.1 or less, there is no worry that the above-mentioned effect of the present invention is remarkably lowered.
Note that the polarized light scattering portion 70 may be formed between the support substrate 1 and the transparent electrode 2, unlike FIG. 3. Even if the support substrate 1 (glass substrate) is present on the polarized light scattering portion 70, the above-described effect of the present invention is similarly achieved.

The shape of the polarized light scattering portion 70 is not particularly limited as long as it has at least two opposing flat surfaces. However, from the viewpoint of use as a polarized light source and the efficiency of total reflection, a film shape, a sheet shape, a plate The film shape is preferable, and among them, the film shape is desirable from the viewpoint of ease of handling. The thickness is preferably 10 mm or less, more preferably 0.1 to 5 mm, and most preferably 0.4 to 2 mm.
The smoothness of the two opposing surfaces is better as it is closer to the mirror surface from the viewpoint of the confinement efficiency of the emitted light by total reflection. If the two facing surfaces are poor in smoothness, a translucent film or sheet excellent in smoothness is separately bonded with a transparent adhesive or adhesive, and a translucent film with a total reflection interface is bonded. The same effect can be obtained by making the sheet a smooth surface.

  The formation of the polarized light scattering portion 70 is different in birefringence by, for example, one or more suitable materials having excellent transparency, such as polymers and liquid crystals, by an appropriate alignment treatment such as a stretching treatment. It can be performed by an appropriate method such as a method of obtaining an oriented film by using the combination for forming the region. Incidentally, examples of the combination include a combination of polymers and liquid crystals, a combination of isotropic polymer and anisotropic polymer, a combination of anisotropic polymers, and the like. The combination of phase separation is preferable from the viewpoint of dispersion distribution in a minute region, and the dispersion distribution can be controlled by the compatibility of the materials to be combined. The phase separation can be performed by an appropriate method such as a method in which an incompatible material is made into a solution with a solvent, or a method in which an incompatible material is mixed under heating and melting.

When the orientation treatment is performed by the above-mentioned combination in the above-described combination, the combination of polymers and liquid crystals and the combination of isotropic polymer and anisotropic polymer are stretched at an arbitrary stretching temperature or stretch ratio, and the combination of anisotropic polymers is stretched. By appropriately controlling the conditions, the target polarized light scattering site can be formed.
The anisotropic polymer is classified as positive or negative based on the property of change in refractive index in the stretching direction. In the present invention, any positive or negative anisotropic polymer can be used, and positive or negative, or positive or negative. Any combination of these can be used.

  Examples of the above-described polymers include, for example, ester polymers such as polyethylene terephthalate and polyethylene naphthalate, styrene polymers such as polystyrene and acrylonitrile / styrene copolymers, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, Examples thereof include olefin polymers such as ethylene / propylene copolymers, acrylic polymers such as polymethyl methacrylate, cellulose polymers such as cellulose diacetate and cellulose triacetate, and amide polymers such as nylon and aromatic polyamide.

  Also, carbonate polymer, vinyl chloride polymer, imide polymer, sulfone polymer, polyether sulfone, polyether ether ketone, polyphenylene sulfide, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate Polymer, polyoxymethylene, silicone polymer, urethane polymer, ether polymer, vinyl acetate polymer, blend of the above polymers, or phenolic, melamine, acrylic, urethane, urethane acrylic, epoxy, silicone Examples of the above-described polymers include thermosetting type and ultraviolet curable type polymers such as a system.

Examples of liquid crystals include, for example, cyanobiphenyl-based, cyanophenylcyclohexane-based, cyanophenyl ester-based, benzoic acid phenyl ester-based, phenylpyrimidine-based, and mixtures thereof that exhibit a nematic or smectic phase at room temperature or high temperature. Examples thereof include molecular liquid crystals, crosslinkable liquid crystal monomers, and liquid crystal polymers exhibiting a nematic phase or a smectic phase at room temperature or high temperature.
The above-mentioned crosslinkable liquid crystal monomer is usually subjected to an alignment treatment and then subjected to a crosslinking treatment by an appropriate method using heat, light, or the like to obtain a polymer.

In order to obtain a polarized light scattering site 70 having excellent heat resistance and durability, a glass transition temperature of 50 ° C. or higher, particularly 80 ° C. or higher, particularly 120 ° C. or higher, and a crosslinkable liquid crystal monomer or liquid crystal polymer are used. It is preferable to use in combination.
As the liquid crystal polymer, appropriate ones such as a main chain type and a side chain type can be used, and the kind thereof is not limited. The liquid crystal polymer that can be preferably used in view of the formability and thermal stability of a fine region having excellent uniformity of particle size distribution, moldability to a film, and ease of alignment treatment, has a degree of polymerization of 8 or more, particularly 10 or more, especially 15 to 5,000.
In order to form a polarized light scattering site using this liquid crystal polymer, one or more kinds of polymers and one or more kinds of liquid crystal polymers for forming a fine region are mixed, and the liquid crystal polymer is made minute. For example, a method may be used in which a polymer film dispersed and contained in the state of the region is formed and oriented by an appropriate method to form regions having different birefringence.

From the viewpoint of controllability of the refractive index differences Δn ₁ and Δn ₂ due to the alignment treatment, those having a glass transition temperature of 50 ° C. or higher and exhibiting a nematic liquid crystal phase in a temperature range lower than the glass transition temperature of the polymers used together. Are preferably used.
Specifically, the following general formula (A);
(-X-) n
| (A)
Y-Z
And a side chain type liquid crystal polymer having a monomer unit represented by the formula:
Such a side chain type liquid crystal polymer may be an appropriate thermoplastic polymer such as a homopolymer or copolymer having a monomer unit represented by the general formula (A), and preferably has excellent monodomain orientation. .

In the general formula (A), X is a skeleton group that forms the main chain of the liquid crystal polymer, and may be composed of an appropriate connecting chain such as linear, branched, or cyclic. Specifically, polyacrylates, polymethacrylates, poly-α-haloacrylates, poly-α-cyanoacrylates, polyacrylamides, polyacrylonitriles, polymethacrylonitriles, polyamides, polyesters, polyurethanes , Polyethers, polyimides, polysiloxanes and the like.
Y is a spacer group branched from the main chain, and from the viewpoint of the formation of polarized light scattering sites such as refractive index control, ethylene, propylene, butylene, pentylene, hexylene, octylene, decylene, undecylene, dodecylene, octadecylene, Preferred are ethoxyethylene, methoxybutylene and the like. Z is a mesogenic group that imparts liquid crystal alignment.

The formation of polarized light scattering sites using nematic alignment liquid crystal polymer consists of polymers for forming a polymer film and a glass transition temperature exhibiting a nematic liquid crystal phase in a temperature range lower than the glass transition temperature of the polymers. A liquid crystal polymer of 50 ° C. or higher, particularly 60 ° C. or higher, particularly 70 ° C. or higher is mixed to form a polymer film containing the liquid crystal polymer dispersed in a minute region, and the liquid crystal polymer forming the minute region is heat-treated. This can be achieved by aligning the nematic liquid crystal phase and cooling and fixing the alignment state.
Formation of the polymer film containing the fine regions dispersedly, that is, the film to be subjected to the orientation treatment can be produced by an appropriate method such as a casting method, an extrusion molding method, an injection molding method, a roll molding method, or a casting method. It can also be carried out by a method of developing in a monomer state and polymerizing it by heat treatment or radiation treatment such as ultraviolet rays to form a film.

Rather than the point of obtaining a polarization disturbing portion 70 having excellent uniform distribution in a minute region, a method of forming a film of a mixture of a forming material through a solvent by a casting method or a casting method is adopted. Is preferred. In this case, the size and distribution of the micro area can be appropriately controlled by the type of solvent, the viscosity of the mixed liquid, the drying speed of the mixed liquid spreading layer, and the like. Incidentally, to reduce the area of the minute region, it is advantageous to reduce the viscosity of the mixed liquid or to accelerate the drying speed of the mixed liquid spreading layer.
The thickness of the film to be subjected to the alignment treatment can be determined as appropriate, but it is usually 1 μm to 3 mm, particularly 5 μm to 1 mm, and more preferably 10 to 500 μm from the viewpoint of alignment processability. In forming the film, for example, appropriate additives such as a dispersant, a surfactant, a color tone modifier, a flame retardant, a release agent, and an antioxidant may be blended.

The orientation treatment is a uniaxial, biaxial, sequential biaxial, Z-axial, etc. stretching treatment method, rolling method, applying an electric field or a magnetic field at a temperature equal to or higher than the glass transition temperature or liquid crystal transition temperature, and quenching to fix the orientation. One or two of various methods capable of controlling the refractive index by orientation, such as a method, a method of fluid orientation during film formation, and a method of self-aligning liquid crystals based on a slight orientation of an isotropic polymer The above can be used. Therefore, the obtained polarized light scattering member 70 may be a stretched film or a non-stretched film.
In the case of a stretched film, a brittle polymer can be used, but a polymer having excellent extensibility can be particularly preferably used.

When the minute region is composed of a liquid crystal polymer, the liquid crystal polymer dispersed and distributed as the minute region in the polymer film is heated to melt at a temperature at which the desired liquid crystal phase such as a nematic phase is exhibited, and is subjected to the alignment regulating force. It can also be performed by a method in which the alignment state is rapidly cooled to fix the alignment state. The orientation state of the minute region is preferably in a monodomain state as much as possible from the viewpoint of preventing variation in optical characteristics.
For the above-mentioned alignment regulating force, an appropriate regulating force that can orient the liquid crystal polymer, such as stretching force by a method of stretching a polymer film at an appropriate magnification, sharing force at the time of film formation, electric field or magnetic field can be applied. The alignment treatment of the liquid crystal polymer can be performed by applying one or more kinds of regulating forces.

Therefore, the portion other than the minute region in the polarized light scattering portion may be birefringent or isotropic.
The whole of the polarized light-scattering part exhibiting birefringence can be obtained by molecular orientation in the above-described film forming process using oriented birefringent polymers for film formation, and if necessary The birefringence can be imparted or controlled by adding a well-known orientation means such as a court extension process.
The polarized light scattering part where the part other than the minute region is isotropic uses an isotropic material for forming the film, and the film is stretched in a temperature region below the glass transition temperature of the polymer. It can be obtained by a method.

In the present invention, the refractive index differences Δn ₁ , Δn ₂ , Δn ₃ in the respective optical axis directions of the minute region show the maximum values between the minute region and the other portion, that is, the portion made of a translucent resin. It is 0.03 to 0.5 (Δn ₁ ) in the axial direction (Δn ₁ direction) and 0.03 or less (Δn ₂ ) in two axial directions (Δn ₂ direction and Δn ₃ direction) perpendicular to the Δn ₁ direction. , Δn ₃ ), and it is preferable that Δn ₂ and Δn ₃ are equal. By making such a refractive index difference, linearly polarized light in the Δn ₁ direction is strongly scattered and scattered at an angle smaller than the critical angle, and the amount of light emitted from the polarized light scattering part can be increased. Linearly polarized light is difficult to scatter and repeats total reflection so that it can be confined in a polarized light scattering region.
Note that the difference in refractive index between the direction of each optical axis of the micro area and the portion other than the micro area is the refractive index in the direction of the optical axis of the micro area when the translucent resin is optically isotropic. It means the difference from the average refractive index of the translucent resin. Further, in the case of optical anisotropy, the main optical axis direction of the translucent resin and the main optical axis direction of the minute region are usually coincident with each other. It means a difference.

In the present invention, it is preferable that the refractive index difference Δn ₁ in the Δn ₁ direction is reasonably large from the point of total reflection described above, particularly 0.035 to 0.5, particularly 0.040 to 0.45. Is preferred. Further, the difference in refractive index Δn ₂ and Δn ₃ between the Δn ₂ direction and the Δn ₃ direction is preferably as small as possible and is preferably zero as much as possible. Such a refractive index difference can be controlled by the refractive index of the material used or the above-described orientation operation.
Further, the Δn ₁ direction is preferably a plane of vibration of linearly polarized light emitted from the polarized light scattering portion, so that this Δn ₁ direction is preferably parallel to two opposing surfaces of the polarized light disturbing portion. . Note that the Δn ₁ direction in the plane can be set to an appropriate direction according to a target liquid crystal cell or the like.

It is preferable that the miniaturized region in the polarized light scattering part is distributed and distributed as evenly as possible from the viewpoint of homogeneity such as scattering effect. The size of the minute region, particularly the length in the Δn ₁ direction, which is the scattering direction, is related to backscattering (reflection) and wavelength dependency. Desirable size of the small area from the viewpoints of improving light utilization efficiency and preventing coloration due to wavelength dependence, preventing visual obstruction due to visual perception of minute areas or preventing clear display, and film forming properties and film strength. In particular, the preferable length in the Δn ₁ direction is 0.05 to 500 μm, particularly 0.1 to 250 μm, and more preferably _{1 to} 100 μm. Incidentally, the minute area is present in the polarization scattering within the site in the form of customary domain is not particularly limited to the length of such that [Delta] n _2.
The proportion of the minute region in the polarized light scattering region 70 can be appropriately determined from the viewpoint of the scattering property in the Δn ₁ direction, but generally 0.1 to 70 in view of the film strength and the like. It is desirable to set it as weight%, and it is more desirable to set it as 0.5 to 50 weight% especially, and it is still more desirable to set it as 1 to 30 weight% especially.

In the present invention, the polarization scattering portion 70 can be formed of a single layer or can be formed as two or more layers superimposed. By superimposing, a synergistic scattering effect more than thickness increase can be exhibited. The superposed body is preferably a superposed body so that the Δn ₁ direction is in a parallel relationship between the upper and lower layers, rather than the point of expansion of the scattering effect. The number of overlapping can be an appropriate number of two or more layers. The polarization scattering sites to be superimposed may be the same in Δn ₁ or Δn ₂ or may be different.
Note that the parallel relationship between the upper and lower layers in the Δn ₁ direction and the like is preferably as parallel as possible, but deviation due to work error is allowed. Further, when there is variation in the Δn ₁ direction, it is based on the average direction.

The polarized light scattering portion 70 preferably has a phase difference as a whole or a part of the surface light source because the polarization state needs to be appropriately eliminated in the process of transmitting light through this portion. Basically, the slow axis of the polarized light scattering site and the polarization axis (vibration plane) of linearly polarized light that is difficult to scatter are orthogonal to each other. It is considered that the angle changes and polarization conversion occurs.
Although the thickness varies depending on the thickness of the polarized light scattering part rather than the point of polarization conversion, it is generally preferable that there is an in-plane retardation of 5 nm or more. The phase difference is imparted by a method that contains birefringent fine particles, a method that adheres to the surface, a method that makes the translucent resin birefringent, a method that uses them in combination, and a birefringent film that is integrally laminated. It can be performed by an appropriate method such as.

  Further, in the present invention, instead of forming the polarization scattering portion 70, a light diffusion layer similar to the case of the organic EL element shown in FIG. By forming a lens structure and installing a reflective polarizer further on the observer side than this region, the emitted light can be extracted efficiently as polarized light, and absorption at the polarizing plate can be minimized. An organic EL element can be produced.

FIG. 4 shows an example of this organic EL element, which has a transparent electrode 2, a hole transport layer 4, and a light emitting region 6 on the support substrate 1 as in the case of the organic EL element shown in FIG. 1. After having a structure in which the electron-transporting light-emitting layer 5 and the reflective electrode 3 are sequentially laminated to satisfy the formula (1) and preferably to satisfy the formula (2), A light diffusing layer, a lens structure, or the like is formed as the region 7 in which the refraction angle is disturbed, and a reflective polarizer 8 is provided on the observer side from the region 7.
The reflective polarizer 8 supplies transmitted light composed of polarized light obtained by making the emitted light guided through the region 7 incident to the polarizing plate to reduce absorption loss, and reflects the reflected light from the reflective polarizer 8. Inverted through the reflective layer in the surface light source device and re-entered the reflective polarizer, part or all of it is transmitted through the absorptive polarizing plate as the predetermined polarization, and the amount of light that can be used for liquid crystal display etc. is increased Thus, the luminance is improved. From the viewpoint of improving the luminance, a reflective polarizer having a polarized light reflectance of 40% or more is preferable.

As such a reflective polarizer 8, an appropriate one that allows reflected light and transmitted light to be obtained by entering natural light is used. Specifically, a reflective circular polarizer (circularly polarized light separating sheet) composed of a cholesteric liquid crystal layer, and a reflective linear polarizer (linearly polarized light separating sheet) formed by laminating at least two kinds of materials having different refractive indexes ( For example, JP-A-9-506984, JP-A-9-507308, and the like.
The reflection type circular polarizer is composed of a cholesteric liquid crystal layer having a Grandjean orientation, and separates incident light into reflected light and transmitted light composed of left and right circularly polarized light. The reflective linear polarizer separates incident light into reflected light and transmitted light composed of linearly polarized light whose vibration planes are orthogonal to each other, and there are commercially available products such as “DBEF” manufactured by 3M.

In the reflective circular polarizer, as the cholesteric liquid crystal layer, an appropriate material that reflects incident light as light that is composed of left and right circularly polarized light and transmits other light can be used. There is no particular limitation on the type.
A reflective circular polarizer is usually obtained as a film made of a cholesteric liquid crystal polymer or a cholesteric liquid crystal layer in close contact with and supported on a transparent substrate. In order to obtain transmitted circularly polarized light in a wide wavelength range, a structure in which two or three or more cholesteric liquid crystal layers having different reflection wavelength ranges are superimposed may be used.
When the organic EL element of the present invention is used as a backlight for a liquid crystal display device, the light emitted from the reflective circular polarizer is circularly polarized light, but it can be easily linearized by using a quarter-wave plate or the like. It can be changed to polarized light.

  In the present invention, the reflective polarizer 8 only needs to be formed on the observer side, that is, outside the region 7 where the reflection / refraction angle of light is disturbed. In that case, it may be installed through an air layer, may be directly adhered to the region 7, or may be bonded through an adhesive or a pressure-sensitive adhesive, and is not particularly limited. A layer having another function such as a moisture-proof layer may be added between the region 7 and the reflective polarizer 8. 5 to 7 show examples other than FIG.

In FIG. 5, a region 7 in which the reflection / refraction angle of light is disturbed is provided adjacent to the transparent electrode 2, and a reflective polarizer 8 is provided via the support substrate 1. In FIG. 6, a region 7 in which a microlens structure is formed on the surface of the support substrate 1 is used as the region 7 in which the reflection / refraction angle of light is disturbed, and a reflective polarizer 8 is provided through an air layer. Is. The other constituent elements are the same as those in FIG.
FIG. 7 shows a reflective electrode 3, an electron transporting light emitting layer 5, a hole transporting layer 4, a transparent electrode 2, a region 7 in which the reflection / refraction angle of light is disturbed, and a reflective polarizer on the support substrate 1. 8 is an example of a so-called upper surface extraction method in which 8 is provided in this order and emitted light is extracted from the opposite surface side of the support substrate 1. In this case, the support substrate 1 does not need to be transparent.

The organic EL element having the above configuration is optimal as a light source for a backlight for a liquid crystal display device because emitted light is obtained as polarized light. It is optimal for applications that require low power consumption due to the light weight, thinness, and battery capacity, such as mobile phones and mobile devices.
FIG. 8 shows an application example in which a reflective circular polarizer made of a cholesteric liquid crystal layer is used as the reflective polarizer 8 in the organic EL element shown in FIG. In this case, the organic layer in the organic EL element is a thin layer of 500 nm or less at most, and the region 7 that causes disturbance in the reflection / refraction angle of light can be formed with 200 μm or less (thickness up to about 50 μm). Therefore, by reducing the thickness of the glass plate as the support substrate 1 or using a resin film, it is possible to reduce the thickness and weight as compared with a conventional backlight using a light guide plate.

In FIG. 8, the guided light component is strengthened by the organic EL element having the above-described configuration, and the total amount of light is essentially amplified. . Half of the light incident on the reflective polarizer 8 is transmitted as circularly polarized light, and the other half is reflected as opposite circularly polarized light. This circularly polarized light enters the region 7 again and is depolarized by being scattered, and is backscattered as natural light in the region 7 or reflected by the reflective electrode 3 and incident on the reflective polarizer 8 again. Half is transmitted as circularly polarized light.
By repeating this process, 50% or more of emitted light is guided to the outside. The circularly polarized light that has passed through the reflective polarizer 8 is converted into linearly polarized light by the quarter-wave plate 9, and the polarizing direction of the polarizing plate 10 is matched with the vibration direction of the polarizing plate 10 of the liquid crystal display cell. Without being absorbed by the liquid crystal cell 11 and is incident on the liquid crystal cell 11 as it is.

The quarter wave plate for converting circularly polarized light into linearly polarized light has a surface retardation of 1/4 as a retardation film. However, with respect to light in an oblique direction, it is exactly 1/4 from the change in optical path length. Does not function as a wavelength. For this reason, light in an oblique direction is not completely converted from circularly polarized light to linearly polarized light, and thus absorption occurs in part of the polarizing plate.
In order to improve this, an optical compensation layer (plate) having no anisotropy in the in-plane direction and having a refractive index in the thickness direction larger than the in-plane refractive index can be improved. Further, the quarter wavelength plate itself used may have a refractive index change in the thickness direction, and an optical compensation function may be added.
These optical compensation methods are disclosed in, for example, JP-A-11-231132. In the present invention, these optical compensation methods are not limited in any way, and the materials used are not particularly limited.
In addition, strictly speaking, the polarization state and the polarizer in the present invention are not completely linearly polarized light and circularly polarized light, but are actually slightly elliptically polarized from them. This is referred to as circularly polarized light, and the effect of the present invention is sufficiently exhibited even if it is not necessarily in a completely polarized state.

In the organic EL element of the present invention, there is no limitation on the organic material, electrode material, layer configuration, film thickness of each layer, and the like, which are the basic configuration, and the conventional technology can be applied as it is.
Specifically, the anode / hole transport layer / electron transporting light-emitting layer / cathode as well as the above-described two-layer organic EL element, as well as the anode / hole transport layer as a three-layer organic EL element. Various configurations such as: / light emitting layer / electron transport layer / cathode, and anode / light emitting layer / cathode different from these stacked elements can be selected, and there is no particular limitation.
Alternatively, a hole injection layer may be provided at the anode interface or an electron injection layer at the cathode interface, or an electron block layer or a hole block layer may be inserted to increase recombination efficiency. Basically, by selecting a configuration, material, and formation method with higher luminous efficiency, strong EL emission can be obtained with less power consumption, and the effects of the present invention can be further enhanced.

Further, in the organic EL device of the present invention, when one of the cathode electrode and the anode electrode is a transparent electrode and the other is a reflective electrode having as high a reflectance as possible, the interference effect appears more prominently. The other is not necessarily a reflective electrode.
Both electrodes may be transparent electrodes, or the reflective electrode may be a semi-transparent electrode with relatively low reflectivity. Conversely, it is an electrode with extremely high reflectivity composed of a dielectric mirror or the like. In short, it is important that the expression (1) is satisfied.

As the electrode material, an optimal material can be selected as appropriate. In a normal organic EL device, indium tin oxide (ITO) is used for the anode, a transparent conductive film typified by a material in which a dopant is added to tin oxide or zinc oxide, and Mg and Ag are about 10: Co-deposited at an atomic ratio of 1, a Ca electrode, an Al electrode doped with a small amount of Li are applied from the viewpoint of improving the electron injection efficiency by lowering the work function of the cathode, but are not particularly limited.
In addition to using a transparent electrode such as ITO as the anode, a thin metal electrode capable of maintaining translucency of several nanometers to several tens of nanometers from the interface of the organic layer is formed as the cathode, and then ITO is formed. Thus, the cathode may be a transparent electrode. Alternatively, the anode and the cathode may be made into a transparent electrode in the same manner as described above, and a double-sided take-out structure in which light emission is taken out from both the anode and the cathode may be formed. Also good.

The case where the light emission distribution on both sides of the cathode and the anode satisfies the formula (1) is most preferable, but the effect of the present invention can be exhibited if either one satisfies the formula (1). A region in which the reflection / refraction angle is disturbed may be formed on both sides, or may be formed only on one side, or may have different characteristics. Even if it forms in the surface which does not satisfy | fill Formula (1), the effect of this invention is not impaired and it can select arbitrarily according to a use.
As a method for making a double-sided extraction structure, a method in which a low work function metal typified by an alkali metal is mixed in an organic layer and electrons can be injected from an ITO electrode (Matsumoto, “OPTRONICS” No. 2, p. 136, 2003). ), And a method of inserting a metal complex material such as copper phthalocyanine between the electron transport layer and ITO (Asuka et al., Appl. Phys. Lett., Vol. 78, p. 3343, 2001).

In the present invention, the material of the organic layer (organic EL material) is not limited, and any of a low molecular weight type and a high molecular weight type can be suitably used. That is, a low molecular material may be formed by vacuum deposition, or a high molecular material may be formed by a coating method or the like, and there is no particular limitation.
Even in a polymer organic EL element, an organic EL element satisfying the formula (1) can be produced depending on the size of the electron mobility and hole mobility and the element configuration, and a part that traps either carrier. It is possible to limit the recombination light-emitting region to a specific site by satisfying the formula (2).
For example, in the case of a single-layer element of transparent electrode (anode) / light emitting layer / reflecting electrode (cathode), recombination is mainly performed by reflecting electrode by making the electron transporting property of the light emitting layer larger than the hole transporting property. Since it can be generated on the anode side that is more distant, Formula (1) and Formula (2) can be satisfied by appropriately adjusting the film thickness of the light emitting layer. Examples of the material having carrier trapping properties include polyphenylene vinylene derivatives reported by Matsumura et al. (M. Matsumura et al., Appl. Phys. Lett., Vol. 79, p. 4491, 2001). There are copolymers.

  In the organic EL device of the present invention, a general substrate can be used regardless of the presence or absence of transparency. In addition to a method of using a glass substrate and extracting light emission to the glass substrate side through a transparent electrode, an opaque metal plate may be used for the support substrate, and light may be extracted from the opposite direction to the support substrate. For the support substrate, a flexible material such as a polymer film may be used, or the support substrate itself may be formed with a region in which the reflection / refraction angle of light is disturbed. Moreover, you may form the area | region which produces disorder in the reflection and refraction angle of light between a support substrate and a transparent electrode. In the present invention, even if the support substrate is on a region where the reflection / refraction angle of light is disturbed, the effects of the present invention are similarly obtained.

When a polymer film is used as the support substrate, specific materials include polyethylene terephthalate, triacetylcellulose, polyethylene naphthalate, polyethersulfone, polycarbonate, polyacrylate, polyetheretherketone, norbornene resin, and the like. It is done.
When the support substrate is located on the exit surface side of the polarization scattering site, which is a region that causes disturbance in the reflection / refraction angle of light, the support substrate has a plurality of layers to maintain the linearly polarized light obtained by the polarization scattering site. It is necessary to select one having no optical anisotropy showing refraction.
If there is birefringence, the linearly polarized light emitted from the polarized light scattering part and the optical axis and phase difference of the linearly polarized light are converted into elliptically polarized light. Component may increase. Therefore, it is necessary to use a glass plate, an epoxy resin substrate, a cellulose triacetate film, a norbornene-based resin film, or other commercially available substrates having no optical anisotropy as the support substrate in this case.

In the organic EL device of the present invention, when a polarized light scattering portion is formed as a region that causes disturbance in the reflection / refraction angle of light, a polarization maintaining lens sheet, a light diffusion plate, a wavelength cut filter is provided on the light extraction surface. A retardation film or the like can be used as appropriate.
The lens sheet improves the directivity in the front direction, which is advantageous for visual recognition, by controlling the optical path while maintaining the degree of polarization of the emitted light (linearly polarized light) as much as possible. The purpose is to set the direction.
The wavelength cut filter is used for the purpose of preventing the direct light from the excitation light source from entering, for example, a liquid crystal display element. Especially when the excitation light is ultraviolet light, it is necessary to prevent the deterioration of the liquid crystal and the polarizing plate due to the ultraviolet light. There is. It can also be used for the purpose of eliminating visible light having an unnecessary wavelength. Further, in the present invention, without providing the above-described wavelength cut filter, for example, an ultraviolet absorber can be added to the polarized light scattering site and other components to provide a wavelength cut function.

  The organic EL element of the present invention can provide a surface light source having a high light emission efficiency and a display device including the surface light source by having the specific structure as described above as a light emitting element. In particular, a light scattering layer or a lens is used as a region in which a polarization-scattering part is formed as a region causing disturbance in the reflection / refraction angle of light in the organic EL element, or as a region causing disturbance in the reflection / refraction angle of light. In the case where a structure or the like is formed and a reflective polarizer is installed, a polarization plane light source having high luminous efficiency comprising these as light emitting elements and a display device such as a liquid crystal display comprising the polarization plane light source can be provided. It is.

  Next, in the organic EL device of the present invention, “Examples 1-1 to 6” and “Comparison” in which a light diffusion layer (light diffusable adhesive) or a lens structure is provided as a region that causes disturbance in the reflection / refraction angle. Examples 1-1 to 6 "are described to illustrate the present invention.

Example 1-1
<Production of basic structure of organic EL element>
An ITO film having a thickness of 100 nm is formed on one side of a glass substrate from an ITO ceramic target (In ₂ O ₃ : SnO ₂ = 90% by weight: 10% by weight) by a DC sputtering method, and a transparent electrode (anode) Formed.
Thereafter, ITO was etched using a photoresist to form a pattern so that the light emitting area was 15 mm × 15 mm. After ultrasonic cleaning, ozone cleaning was performed using a low-pressure ultraviolet lamp.

  Next, organic layers were sequentially formed on the ITO surface by vacuum deposition. First, as a hole injection layer, CuPc represented by the formula (3) was formed to a thickness of 15 nm at a deposition rate of 0.3 nm / s. Next, α-NPD represented by Formula (4) was formed to a thickness of 40 nm at a deposition rate of 0.3 nm / s as a hole transport layer. Finally, as the electron transporting light emitting layer, Alq represented by the formula (5) was formed to a thickness of 140 nm at a deposition rate of 0.3 nm / s.

Thereafter, Mg is co-deposited at a deposition rate of 1 nm / s and Ag is 0.1 nm / s to form MgAg with a thickness of 100 nm, and from the viewpoint of preventing oxidation of MgAg, 50 nm of Ag is further formed thereon. Thus, a reflective electrode (cathode) was obtained.
After taking out from the vacuum deposition device, drop the ultraviolet curable epoxy resin on the cathode electrode side, cover it with a slide glass, and when the epoxy resin spreads sufficiently, cure the epoxy resin using a high pressure ultraviolet lamp, The element was sealed.

When a voltage of 15 V was applied to the organic EL element before forming the region in which the reflection / refraction angle was disturbed thus produced, current was passed through the element at a current density of 10.5 mA / cm ² , and light emission occurred. Was observed.
As shown in FIG. 10, using a commercially available luminance meter (product name “BM9” manufactured by Topcon Co., Ltd.), the luminance of the element in the θ direction was measured every 10 degrees from 0 degrees to 80 degrees. The result shown in -1. Moreover, when the measurement angle was changed in the φ direction and the angle dependency of the luminance was measured, the luminance value was almost the same in all directions.
Therefore, in the φ direction, it is assumed that the light emission is uniformly distributed, and the amount of luminous flux per unit area (lm / m ² ) emitted to the space up to the 80 ° direction is calculated by numerical integration. did. The results are also shown in Table 1-1.

As shown in Table 1-1, the organic EL element sufficiently satisfies the relationship of the formula (1) of the present invention. In this element, the recombination of holes and electrons occurs at the interface between α-NPD and Alq. Therefore, the distance d between the central portion of the hole-electron recombination light-emitting region and the reflective electrode in the present invention was about 140 nm.
The peak wavelength λ of the fluorescence spectrum when the Alq thin film deposited on the glass substrate was irradiated with black light having an emission wavelength of 365 nm as the excitation light source was about 530 nm. The refractive index n of the Alq thin film measured with a spectroscopic ellipsometer was about 1.67. Therefore, said organic EL element was also satisfying the relationship of Formula (2) of this invention.

<Formation of regions that cause disturbance in reflection and refraction angles>
To 50 g of toluene, 25 g of silicone particles having a refractive index of 1.43 and a particle diameter of 4 μm were added and stirred well. An acrylic pressure-sensitive adhesive having a refractive index of 1.47 was added to toluene and dissolved. This solution is added to the toluene solution in which the silicone particles are dispersed so that the silicone concentration with respect to the adhesive is 25% by weight, and the concentration is adjusted so that the concentration of the adhesive with respect to toluene is 25% by weight. And stirred well.
Using the applicator, the prepared solution was applied onto the separator and dried to prepare a 20 μm thick light-diffusing adhesive.

Next, on the glass substrate surface of the organic EL element produced as described above, 10 pieces of the above light diffusive pressure-sensitive adhesives were stacked and bonded together to form a light diffusion layer having a thickness of about 200 μm. Thereafter, in the same manner as described above, a voltage of 15 V was applied to the device, and the luminance when a current was passed through the device at a current density of 10.5 mA / cm ² was measured in the range of 0 to 80 degrees. The results are shown in Table 1-1. Further, the amount of light flux per unit area was calculated in the same manner as described above and shown in Table 1-1.

Table 1-1
┌──────┬───────────────────────┐
│ Angularity │ Luminance value (cd / m ² ) │
│ ├───────────┬───────────┤
│ │ Before light diffusion layer formation │ After light diffusion layer formation │
├──────┼───────────┼───────────┤
│ 0 ° │ 126 │ 392 │
│ 10 ° │ 138 │ 382 │
│ 20 ° │ 154 │ 382 │
│ 30 ° │ 181 │ 424 │
│ 40 ° │ 225 │ 445 │
│ 50 ° │ 272 │ 466 │
│ 60 ° │ 307 │ 509 │
│ 70 ° │ 386 │ 487 │
│ 80 ° │ 339 │ 466 │
├──────┼───────────┼───────────┤
│ Total light quantity │ 761 (lm / m ² ) | 1374 (lm / m ² ) |
└──────┴───────────┴───────────┘

Example 1-2
An organic EL element as a basic structure, and light scattering thereto, as in Example 1-1, except that Alq represented by the formula (5) was formed to a thickness of 120 nm as the electron-transporting light-emitting layer. The organic EL element in which the layer was formed was produced.
A voltage of 13.1 V was applied to the organic EL element before and after the formation of the light diffusion layer, and a current was passed through the element at a current density of 10.5 mA / cm ^{2 in} the same manner as in Example 1-1. evaluated. These results are shown in Table 1-2. The luminance distribution in the θ direction before forming the light diffusing layer satisfies the relationship of the formula (1) of the present invention, and the value of the Alq layer 120 nm also satisfies the relationship of the formula (2) of the present invention. It was a thing.

Table 1-2
┌──────┬───────────────────────┐
│ Angularity │ Luminance value (cd / m ² ) │
│ ├───────────┬───────────┤
│ │ Before light diffusion layer formation │ After light diffusion layer formation │
├──────┼───────────┼───────────┤
│ 0 ° │ 166 │ 426 │
│ 10 ° │ 171 │ 431 │
│ 20 ° │ 176 │ 450 │
│ 30 ° │ 205 │ 460 │
│ 40 ° │ 245 │ 465 │
│ 50 ° │ 284 │ 484 │
│ 60 ° │ 313 │ 499 │
│ 70 ° │ 362 │ 484 │
│ 80 ° │ 342 │ 377 │
├──────┼───────────┼───────────┤
│ total amount ^{│ 798 (lm / m 2)} │1432 (lm / m 2) │
└──────┴───────────┴───────────┘

Comparative Example 1-1
An organic EL element as a basic structure, and light scattering in the same manner as in Example 1-1, except that Alq represented by formula (5) was formed to a thickness of 60 nm as the electron-transporting light-emitting layer. An organic EL element having a layer was produced.
A voltage of 8.2 V was applied to the organic EL element before and after the formation of the light diffusion layer, and a current was passed through the element at a current density of 10.5 mA / cm ² in the same manner to emit light. evaluated. These results are shown in Table 1-3. The luminance distribution in the θ direction before forming the light diffusion layer does not satisfy the relationship of the formula (1) of the present invention, and the value of the Alq layer of 60 nm also satisfies the relationship of the formula (2) of the present invention. It was not something.

Table 1-3
┌──────┬───────────────────────┐
│ Angularity │ Luminance value (cd / m ² ) │
│ ├───────────┬───────────┤
│ │ Before light diffusion layer formation │ After light diffusion layer formation │
├──────┼───────────┼───────────┤
│ 0 ° │ 323 │ 384 │
│ 10 ° │ 323 │ 384 │
│ 20 ° │ 319 │ 384 │
│ 30 ° │ 315 │ 384 │
│ 40 ° │ 302 │ 360 │
│ 50 ° │ 286 │ 336 │
│ 60 ° │ 269 │ 312 │
│ 70 ° │ 244 │ 265 │
│ 80 ° │ 202 │ 143 │
├──────┼───────────┼───────────┤
│ Total light quantity │ 884 (lm / m ² ) │1034 (lm / m ² ) │
└──────┴───────────┴───────────┘

Comparative Example 1-2
An organic EL element as a basic structure, and light scattering in the same manner as in Example 1-1, except that Alq represented by formula (5) was formed to a thickness of 25 nm as the electron-transporting light-emitting layer. An organic EL element having a layer was produced.
A voltage of 6.1 V was applied to the organic EL device before and after the formation of the light diffusion layer, and a current was passed through the device at a current density of 10.5 mA / cm ² to cause the device to emit light, as in Example 1-1. evaluated. These results are shown in Table 1-4. The luminance distribution in the θ direction before forming the light diffusion layer does not satisfy the relationship of the formula (1) of the present invention, and the value of the Alq layer 25 nm also satisfies the relationship of the formula (2) of the present invention. It was not something.

Table 1-4
┌──────┬───────────────────────┐
│ Angularity │ Luminance value (cd / m ² ) │
│ ├───────────┬───────────┤
│ │ Before light diffusion layer formation │ After light diffusion layer formation │
├──────┼───────────┼───────────┤
│ 0 ° │ 123 │ 138 │
│ 10 ° │ 123 │ 138 │
│ 20 ° │ 118 │ 138 │
│ 30 ° │ 114 │ 138 │
│ 40 ° │ 107 │ 137 │
│ 50 ° │ 106 │ 135 │
│ 60 ° │ 102 │ 126 │
│ 70 ° │ 95 │ 116 │
│ 80 ° │ 82 │ 95 │
├──────┼───────────┼───────────┤
│ Total light quantity │ 328 (lm / m ² ) │ 402 (lm / m ² ) │
└──────┴───────────┴───────────┘

Comparative Example 1-3
An organic EL element as a basic structure, and light scattering in the same manner as in Example 1-1, except that Alq represented by Formula (5) was formed to a thickness of 180 nm as the electron-transporting light-emitting layer. The organic EL element in which the layer was formed was produced.
A voltage of 17.3 V was applied to the organic EL device before and after the formation of the light diffusion layer, and a current was passed through the device at a current density of 10.5 mA / cm ² to cause the device to emit light. Evaluation was performed in the same manner as in Example 1. . These results are shown in Table 1-5. The luminance distribution in the θ direction before forming the light diffusion layer does not satisfy the relationship of the formula (1) of the present invention, and the value of the Alq layer of 180 nm also satisfies the relationship of the formula (2) of the present invention. It was not something.

Table 1-5
┌──────┬───────────────────────┐
│ Angularity │ Luminance value (cd / m ² ) │
│ ├───────────┬───────────┤
│ │ Before light diffusion layer formation │ After light diffusion layer formation │
├──────┼───────────┼───────────┤
│ 0 ° │ 154 │ 243 │
│ 10 ° │ 148 │ 240 │
│ 20 ° │ 134 │ 238 │
│ 30 ° │ 116 │ 252 │
│ 40 ° │ 101 │ 267 │
│ 50 ° │ 92 │ 267 │
│ 60 ° │ 95 │ 264 │
│ 70 ° │ 89 │ 243 │
│ 80 ° │ 80 │ 157 │
├──────┼───────────┼───────────┤
│ Total light quantity │ 323 (lm / m ² ) │ 773 (lm / m ² ) │
└──────┴───────────┴───────────┘

Comparative Example 1-4
An organic EL element as a basic structure, and light scattering thereto, as in Example 1-1, except that Alq represented by the formula (5) was formed to a thickness of 220 nm as the electron-transporting light-emitting layer. An organic EL element having a layer was produced.
A voltage of 21.2 V was applied to the organic EL device before and after the formation of the light diffusion layer, and a current was passed through the device at a current density of 10.5 mA / cm ² to cause the device to emit light, as in Example 1-1. evaluated. These results are shown in Table 1-6. The luminance distribution in the θ direction before forming the light diffusion layer does not satisfy the relationship of the formula (1) of the present invention, and the value of the Alq layer 220 nm also satisfies the relationship of the formula (2) of the present invention. It was not something.

Table 1-6
┌──────┬───────────────────────┐
│ Angularity │ Luminance value (cd / m ² ) │
│ ├───────────┬───────────┤
│ │ Before light diffusion layer formation │ After light diffusion layer formation │
├──────┼───────────┼───────────┤
│ 0 ° │ 363 │ 363 │
│ 10 ° │ 354 │ 367 │
│ 20 ° │ 358 │ 354 │
│ 30 ° │ 341 │ 341 │
│ 40 ° │ 311 │ 320 │
│ 50 ° │ 272 │ 332 │
│ 60 ° │ 225 │ 302 │
│ 70 ° │ 177 │ 263 │
│ 80 ° │ 160 │ 207 │
├──────┼───────────┼───────────┤
│ Total amount of light │ 863 (lm / m ² ) 975 (lm / m ² ) |
└──────┴───────────┴───────────┘

The results of Examples 1-1 and 2 are summarized in Table 1-7.
Table 1-7
┌─────────────┬────────┬┬────────┐
│ │ Example 1-1 │ Example 1-2 │
├─────────────┼────────┼┼────────┤
│Alq layer thickness (nm) │ 140 │ 120 │
├─────────────┼────────┼┼────────┤
│Front brightness (cd / m ² ) │ │ │
│ Before light diffusion layer formation │ 126 │ 166 │
│ After light diffusion layer formation │ 392 │ 426 │
│ Increase in brightness │ 3.11 │ 2.56 │
├─────────────┼────────┼┼────────┤
│Total luminous flux (lm / m ² ) │ │ │
│ Before light diffusion layer formation │ 761 │ 798 │
│ After light diffusion layer formation │ 1374 │ 1432 │
│ Increasing light intensity │ 1.81 │ 1.79 │
└─────────────┴────────┴┴────────┘

Moreover, the result of said Comparative Examples 1-1-4 was put together in Table 1-8, and was shown.
Table 1-8
┌────────────┬─────┬─────┬─────┬─────┐
│ │Comparative Example 1-1│Comparative Example 1-2│Comparative Example 1-3│Comparative Example 1-4│
├────────────┼─────┼─────┼─────┼─────┤
│Alq layer thickness (nm) │ 60 │ 25 │ 180 │ 220 │
├────────────┼─────┼─────┼─────┼─────┤
│Front brightness (cd / m ² ) │ │ │ │ │
│ Before light diffusion layer formation │ 323 │ 123 │ 154 │ 363 │
│ After light diffusion layer formation │ 384 │ 138 │ 243 │ 363 │
│ Brightness increase │ 1.19│ 1.13│ 1.58│ 1.00│
├────────────┼─────┼─────┼─────┼─────┤
│Total luminous flux (lm / m ² ) │ │ │ │ │
│ Before light diffusion layer formation │ 884│ 328│ 323│ 863│
│ After light diffusion layer formation │ 1034 │ 402 │ 773 │ 975 │
│ Increasing light quantity │ 1.17│ 1.23│ 2.39│ 1.13│
└────────────┴─────┴─────┴─────┴─────┘

  As is clear from the above results, the organic EL elements of Examples 1-1 and 2 of the present invention did not obtain large values of luminance and total luminous flux before forming the light diffusion layer. After the diffusion layer is formed, both the front luminance and the total luminous flux amount are greatly increased, and the final luminance is higher than that of any of the organic EL elements of Comparative Examples 1-1 to 4 when compared with the same element current. It can be seen that a highly efficient organic EL element can be obtained.

Example 1-3
To 10 g of toluene, 1.5 g of silicone particles having a refractive index of 1.43 and a particle diameter of 4 μm was added and stirred well. In addition, polymethyl methacrylate (PMMA) resin was dissolved in toluene so that the concentration was 20% by weight. This solution was added to the toluene solution in which the silicone particles were dispersed so that the silicone concentration with respect to PMMA was 15% by weight, and the concentration was adjusted so that the concentration of PMMA with respect to toluene was 20% by weight, Stir well.
Then, it coated using the applicator so that the thickness of a PMMA layer might be set to about 200 micrometers on the glass substrate, and the light-diffusion layer was formed.

A Si target was used for the light diffusion layer of the glass substrate, and a reactive sputtering method was used in a mixed gas atmosphere of argon gas and oxygen gas to form SiO ₂ having a thickness of 50 nm. Thereafter, an ITO film having a thickness of 100 nm was further formed on the surface in the same manner as in Example 1-1 to obtain a transparent electrode (anode).
Thereafter, ITO was etched using a photoresist to form a pattern so that the light emitting area was 15 mm × 15 mm. After ultrasonic cleaning, ozone cleaning was performed using a low-pressure ultraviolet lamp.

  Next, organic layers were sequentially formed on the ITO surface by vacuum deposition. First, as a hole injection layer, CuPc represented by the above formula (3) was formed to a thickness of 15 nm at a deposition rate of 0.3 nm / s. Next, α-NPD represented by the above formula (4) was formed to a thickness of 40 nm at a deposition rate of 0.3 nm / s as a hole transport layer. Finally, as the electron transporting light emitting layer, Alq represented by the above formula (5) was formed to a thickness of 140 nm at a deposition rate of 0.3 nm / s.

Thereafter, Mg is co-deposited at a deposition rate of 1 nm / s and Ag is 0.1 nm / s to form MgAg with a thickness of 100 nm, and from the viewpoint of preventing oxidation of MgAg, 50 nm of Ag is further formed thereon. Thus, a reflective electrode (cathode) was obtained.
After taking out from the vacuum deposition device, drop the ultraviolet curable epoxy resin on the cathode electrode side, cover it with a slide glass, and when the epoxy resin spreads sufficiently, cure the epoxy resin using a high pressure ultraviolet lamp, The element was sealed.

When a voltage of 15 V was applied to the organic EL device thus fabricated, current was passed through the device at a current density of 10.5 mA / cm ² and light emission was observed. The front luminance at this time was 418 (cd / m ² ), and the total luminous flux was 1492 (lm / m ² ). From this result, the angle distribution in the θ direction before forming the light diffusion layer satisfies the relationship of the formula (1), and the element configuration itself satisfies the relationship of the formula (2). It was confirmed that the effect of the present invention can be sufficiently exhibited by providing a region that causes a disturbance in the refraction angle.

Example 1-4
In Example 1-1, instead of using a light diffusive adhesive, a corner cube lens sheet in which a large number of triangular pyramids are arranged is used as a region in which the reflection / refraction angle is disturbed. An organic EL element was produced in the same manner as in Example 1-1 except that the organic EL element was bonded to the surface of the glass substrate of the organic EL element.

Comparative Example 1-5
An organic EL device was produced in the same manner as in Example 1-4 except that Alq represented by the formula (5) was formed to a thickness of 60 nm as the electron-transporting light-emitting layer.

For the organic EL elements of Examples 1-4 and Comparative Examples 1-5, the total luminous flux was determined in the same manner as described above. The organic EL element of Example 1-4 was 1792 (lm / m ² ). The organic EL device of Comparative Example 1-5 was 1308 (lm / m ² ), and it was confirmed that the luminous efficiency was increased by using the organic EL device of the present invention.

Example 1-5
In the same manner as in Example 1-1, an ITO film was formed on one surface of a glass substrate, and ozone cleaning was performed using ultrasonic cleaning and a low-pressure ultraviolet lamp.
Next, a PEDOT / PSS solution represented by the formula (6) (“BAYTRON P AI 4083” manufactured by Bayer) is spin-coated on the ITO surface at a rotational speed of 4,000 rpm to form a hole injection layer. The film was formed to a thickness of 30 nm. Thereafter, after drying at 120 ° C. for 2 hours, an organic EL layer was formed as follows with reference to the literature (Mori et al., “Applied Physics” Vol. 61, No. 10, p. 1044, 1992). .

First, 9.88 g of 1,1,2,2-tetrachloroethane as a solvent, 0.12 g of PVK represented by the formula (7) as a hole transporting matrix polymer, and BND represented by the formula (8) Was added as an electron transporting material, and 0.056 g of coumarin 6 represented by the formula (9) was added as a light emitting material, followed by dissolution and mixing to prepare a coating solution. Next, this coating solution was spin-coated on the hole injection layer at a rotational speed of 750 rpm to form an organic EL layer having a thickness of 150 nm.
Then, after drying at 70 degreeC for 1 hour, similarly to Example 1-1, the MgAg / Ag electrode was formed with the vacuum evaporation system, and after taking out from the vacuum evaporation system, the element was sealed. The light emission area was set to 15 mm × 15 mm by a mask used for electrode deposition.

When the voltage of 21 V was applied to the organic EL element before forming the region in which the reflection / refraction angle was disturbed, the current was passed through the element at a current density of 20 mA / cm ^2. Green emission was observed. The luminance at this time was measured every 10 degrees from 0 degrees to 80 degrees in the same manner as in Example 1-1. The amount of light flux per unit area was also calculated in the same manner as in Example 1-1.
Next, 10 sheets of the same light diffusive adhesive as in Example 1 were bonded to the surface of the glass substrate of the organic EL element as the basic structure to form a light diffusion layer having a thickness of about 200 μm. Thereafter, a voltage of 21 V was applied to the device in the same manner as described above, and the luminance when a current was passed through the device at a current density of 20 mA / cm ² was measured. Further, the amount of light flux per unit area was calculated.
These results were as shown in Table 1-9.

Table 1-9
┌─────┬──────────────────────┐
│ Angularity │ Luminance value (cd / m ² ) │
│ ├──────────┬───────────┤
│ │ Before light diffusion layer formation │ After light diffusion layer formation │
├─────┼──────────┼───────────┤
│ 0 ° │ 183 │ 351 │
│ 10 ° │ 183 │ 351 │
│ 20 ° │ 183 │ 351 │
│ 30 ° │ 189 │ 347 │
│ 40 ° │ 196 │ 344 │
│ 50 ° │ 215 │ 330 │
│ 60 ° │ 227 │ 315 │
│ 70 ° │ 233 │ 287 │
│ 80 ° │ 202 │ 222 │
├─────┼──────────┼───────────┤
│ total light ^{│628 (lm / m 2) │1002} (lm / m 2) │
└─────┴──────────┴───────────┘

Comparative Example 1-6
Organic EL before forming a region that causes a disorder in the reflection / refraction angle in the same manner as in Example 1-5, except that the rotation speed when forming the organic EL layer was 2500 ppm and the thickness was 75 nm. The element and the organic EL element which formed the light-diffusion layer in this were produced.
For the organic EL device before and after the formation of the light scattering layer, a voltage of 12.7 V was applied, and the device was caused to emit light by passing a current at a current density of 20 mA / cm ² , and evaluated in the same manner as in Example 1-5. did. These results were as shown in Table 1-10.

Table 1-10
┌─────┬─────────────────────┐
│ Angularity │ Luminance value (cd / m ² ) │
│ ├──────────┬──────────┤
│ │ Before light diffusion layer formation │ After light diffusion layer formation │
├─────┼──────────┼───────────┤
│ 0 ° │ 236 │ 291 │
│ 10 ° │ 236 │ 291 │
│ 20 ° │ 236 │ 289 │
│ 30 ° │ 233 │ 288 │
│ 40 ° │ 230 │ 286 │
│ 50 ° │ 227 │ 284 │
│ 60 ° │ 217 │ 263 │
│ 70 ° │ 205 │ 229 │
│ 80 ° │ 174 │ 180 │
├─────┼──────────┼───────────┤
│ Total amount of light │658 (lm / m ² ) │833 (lm / m ² ) │
└─────┴──────────┴───────────┘

  As is clear from the above results, the organic EL element of Example 1-5 of the present invention has the luminance distribution before forming the light diffusion layer satisfies the formula (1) of the present invention. As a result, the total amount of light increased about 1.6 times by forming the light diffusion layer. On the other hand, in the organic EL element of Comparative Example 1-6, the front luminance was higher than that of Example 1-5 before forming the light diffusion layer, but satisfied the formula (1) of the present invention. As a result, the increase in the total amount of light was about 1.2 times, and the guided light extraction effect due to the diffusion layer formation was poor.

  Next, in the organic EL device of the present invention, “Examples 2-1 to 3” in which polarized light scattering sites are provided as regions in which the reflection / refraction angle is disturbed are described, and this and “Comparative Example 2-1” are described. The present invention will be specifically described in comparison with “˜6” and “Reference Examples 2-1 and 2”.

Example 2-1
In the same manner as in Example 1-1, the thickness of the electron transporting light emitting layer [Alq represented by the formula (5)] is 140 nm, and the relationship of the formulas (1) and (2) of the present invention is satisfied. Then, an organic EL element was formed before forming a region in which the reflection / refraction angle was disturbed.
Next, on the glass substrate of the organic EL element as the basic structure, a film as a polarized light scattering portion formed by the following method as a region causing disturbance in the reflection / refraction angle is passed through an acrylic adhesive. And pasted together.
Thereafter, a voltage of 15 V was applied to the organic EL element in the same manner as in Example 1-1, and the front luminance when a current was passed through the element at a current density of 10.5 mA / cm ² was measured. .
In addition, after setting the polarizing plate on the polarization scattering portion so that the stretching direction of the polarization scattering portion and the transmission axis of the polarizing plate ("NPF-SEG1425DU" manufactured by Nitto Denko Corporation) are parallel, The front luminance was measured in the same manner as described above.

<Formation of polarized light scattering sites>
950 parts by weight of a norbornene-based resin (Arton manufactured by JSR, glass transition temperature 182 ° C.) and a liquid crystal polymer represented by the following formula (10) (glass transition temperature 80 ° C., nematic liquid crystal forming temperature 100 to 290 ° C.) 50 A film having a thickness of 100 μm was formed by a casting method using a 20 wt% dichloromethane solution in which parts by weight were dissolved, and this was stretched three times at 180 ° C., then rapidly cooled, and polarized light scattering. It was set as the film as a sex part.
This polarized light scattering film is a film in which a liquid crystal polymer is dispersed in a domain shape having substantially the same shape in the state of being long axis in the stretching direction in a transparent film made of norbornene resin, and the refractive index difference Δn ₁ is 0. .23 and Δn ₂ and Δn ₃ were 0.029. Further, when the average diameter of the minute region was measured by coloring based on a phase difference by observation with a polarizing microscope, the length in the Δn ₁ direction was about 5 μm.

Example 2-2
In the same manner as in Example 1-2, the thickness of the electron transporting light emitting layer [Alq represented by the formula (5)] is 120 nm, and the relationship of the formulas (1) and (2) of the present invention is satisfied. Then, an organic EL element was formed before forming a region in which the reflection / refraction angle was disturbed.
Next, on the glass substrate of the organic EL element as this basic structure, the film as the polarized light scattering site formed in Example 2-1 was used as an acrylic pressure-sensitive adhesive as a region in which the reflection / refraction angle was disturbed. It was pasted through.
Thereafter, in the same manner as in Example 1-2, a voltage of 13.1 V was applied to the organic EL element, and the front luminance when a current was passed through the element at a current density of 10.5 mA / cm ² was obtained. It was measured. In addition, after setting the polarizing plate on the polarization scattering portion so that the stretching direction of the polarization scattering portion and the transmission axis of the polarizing plate ("NPF-SEG1425DU" manufactured by Nitto Denko Corporation) are parallel, The front luminance was measured in the same manner as described above.

Comparative Example 2-1
As the electron-transporting light-emitting layer, a region that causes disturbance in the reflection / refraction angle is formed in the same manner as in Example 1-1 except that Alq represented by Formula (5) is formed to a thickness of 65 nm. The previous organic EL element was produced. A voltage of 8.8 V was applied to the device, current was passed through the device at a current density of 10.5 mA / cm ² , and light was emitted. Evaluation was performed in the same manner as in Example 1-1.
The results are as follows: 0 °: 314 cd / m ² , 10 °: 315 cd / m ² , 20 °: 312 cd / m ² , 30 °: 309 cd / m ² , 40 °: 298 cd / m ² , 50 °: 285 cd / m ² 60 °: 274 cd / m ² , 70 °: 257 cd / m ² , and 80 °: 229 cd / m ² .
Accordingly, the luminance distribution in the θ direction does not satisfy the relationship of the formula (1) of the present invention, and the value of the Alq layer 65 nm does not satisfy the relationship of the formula (2) of the present invention.

Next, on the glass substrate of the organic EL element as the basic structure produced as described above, the film as the polarization scattering portion formed in Example 2-1 was bonded through an acrylic adhesive. . Similarly to the above, a voltage of 8.8 V was applied to the organic EL element, and the front luminance when a current was passed through the element at a current density of 10.5 mA / cm ² was measured.
In addition, after setting the polarizing plate on the polarization scattering portion so that the stretching direction of the polarization scattering portion and the transmission axis of the polarizing plate ("NPF-SEG1425DU" manufactured by Nitto Denko Corporation) are parallel, The front luminance was measured in the same manner as described above.

Comparative Example 2-2
In the same manner as in Comparative Example 1-2, the thickness of the electron-transporting light-emitting layer [Alq represented by Formula (5)] is 25 nm, and the relationship of Formula (1) and Formula (2) of the present invention is satisfied. The organic EL element before forming the area | region which produces disorder in a reflection and a refraction angle was produced.
Next, on the glass substrate of the organic EL element as this basic structure, the film as the polarized light scattering site formed in Example 2-1 was used as an acrylic pressure-sensitive adhesive as a region in which the reflection / refraction angle was disturbed. It was pasted through.
Thereafter, in the same manner as in Comparative Example 1-2, the front luminance when a voltage of 6.1 V was applied to the organic EL element and a current was passed through the element at a current density of 10.5 mA / cm ² was obtained. It was measured.
In addition, after setting the polarizing plate on the polarization scattering portion so that the stretching direction of the polarization scattering portion and the transmission axis of the polarizing plate ("NPF-SEG1425DU" manufactured by Nitto Denko Corporation) are parallel, The front luminance was measured in the same manner as described above.

Comparative Example 2-3
In the same manner as in Comparative Example 1-3, the thickness of the electron-transporting light-emitting layer [Alq represented by Formula (5)] is 180 nm, and the relationship of Formulas (1) and (2) of the present invention is satisfied. The organic EL element before forming the area | region which produces disturbance in a reflection and a refraction angle was produced.
Next, on the glass substrate of the organic EL element as this basic structure, the film as the polarized light scattering site formed in Example 2-1 was used as an acrylic pressure-sensitive adhesive as a region in which the reflection / refraction angle was disturbed. It was pasted through.
Thereafter, in the same manner as in Comparative Example 1-3, the front luminance of the organic EL element when a current of 10.5 mA / cm ² was passed through the element by applying a voltage of 17.3 V was obtained. It was measured. In addition, after setting the polarizing plate on the polarization scattering portion so that the stretching direction of the polarization scattering portion and the transmission axis of the polarizing plate ("NPF-SEG1425DU" manufactured by Nitto Denko Corporation) are parallel, The front luminance was measured in the same manner as described above.

Comparative Example 2-4
In the same manner as in Comparative Example 1-4, the electron transporting light emitting layer [Alq represented by Formula (5)] has a thickness of 220 nm and satisfies the relationship of Formulas (1) and (2) of the present invention. The organic EL element before forming the area | region which produces disturbance in a reflection and a refraction angle was produced.
Next, on the glass substrate of the organic EL element as this basic structure, the film as the polarized light scattering site formed in Example 2-1 was used as an acrylic pressure-sensitive adhesive as a region in which the reflection / refraction angle was disturbed. It was pasted through.
Thereafter, in the same manner as in Comparative Example 1-4, the front luminance of the organic EL element when a voltage of 21.2 V was applied and a current was passed through the element at a current density of 10.5 mA / cm ² was obtained. It was measured. In addition, after setting the polarizing plate on the polarization scattering portion so that the stretching direction of the polarization scattering portion and the transmission axis of the polarizing plate ("NPF-SEG1425DU" manufactured by Nitto Denko Corporation) are parallel, The front luminance was measured in the same manner as described above.

Comparative Example 2-5
On the glass substrate of the organic EL element as a basic configuration before forming the region that causes disturbance in the reflection / refraction angle produced in Example 2-1, as the polarized light scattering site formed in Example 2-1. Instead of the film, a normal diffusion film in which the microregion produced by the following method does not have birefringence characteristics was bonded through an acrylic adhesive.
Similarly to the above, a voltage of 15 V was applied to the organic EL element, and the front luminance when a current was passed through the element at a current density of 10.5 mA / cm ² was measured.
Moreover, after installing a polarizing plate ("NPF-SEG1425DU" made by Nitto Denko Corporation) on the above normal diffusion film, the front luminance was measured in the same manner as described above.

<Preparation of normal diffusion film>
10 g of toluene was taken, and 1.5 g of silicone particles having a refractive index of 1.43 and a particle size of 4 μm were added thereto and stirred well. In addition, polymethyl methacrylate (PMMA) resin was added to toluene so as to have a concentration of 20% by weight and dissolved. The solution was added to a toluene solution in which silicone particles were dispersed so that the silicone concentration with respect to PMMA was 15% by weight, and the concentration was adjusted so that the concentration of PMMA with respect to toluene was 20% by weight. . Then, it coated with the applicator so that the thickness of a PMMA layer might be set to about 200 micrometers on a glass substrate, it peeled off after drying, and the diffusion film was obtained.

Reference Example 2-1
In Example 2-1, the polarizing plate was directly installed on the glass substrate of the organic EL element as the produced basic structure, and the front luminance was measured.

Reference Example 2-2
In Comparative Example 2-1, a polarizing plate was directly placed on the glass substrate of the organic EL element as the basic structure produced, and the front luminance was measured.

  The results of the above Examples 2-1 and 2, Comparative Examples 2-1 to 5 and Reference Examples 2-1 and 2 are summarized in Table 2. Table 2 also shows the degree of increase in luminance in each example, with the front luminance when the polarizing plate of Reference Example 2-2 is installed as a reference (1.00). A value with a luminance increase degree smaller than 1.00 means that the front luminance is decreased.

Table 2
┌──────┬────┬────┬──────────────────┐
│ │Alq layer │ Light diffusion layer │ Front brightness (cd / m ² ) │
│ │ Film thickness │ Type ├────┬────┬────┬───┤
│ │ (nm) │ │Light diffusing layer│Light diffusing layer│Polarizer │Luminance │
│ │ │ │Before formation │After formation │ After installation │Increase degree│
├──────┼────┼────┼────┼┼────┼────┼───┤
│Reference Example 2-1│ 140│ None │ 126│-│ 58│ 0.40 │
│Reference Example 2-2│ 65│ None │ 314 │-│ 145 │ 1.00 │
├──────┼────┼────┼────┼┼────┼────┼───┤
│Example 2-1│ 140│Polarization scattering│ 126│ 358│ 261│ 1.80 │
│ │ │Film│ │ │ │ │
│Example 2-2│ 120│Polarized scattering│ 166│ 388│ 276│ 1.90 │
│ │ │Film│ │ │ │ │
├──────┼────┼────┼────┼┼────┼────┼───┤
│Comparative Example 2-1│ 65│Polarized scattering│ 314│ 340│ 197│ 1.36 │
│ │ │Film│ │ │ │ │
│Comparative Example 2-2│ 25│Polarized scattering│ 123│ 126│ 67│ 0.46 │
│ │ │Film│ │ │ │ │
│Comparative Example 2-3│ 180│Polarized scattering│ 154│ 222│ 131│ 0.90 │
│ │ │Film│ │ │ │ │
│Comparative Example 2-4│ 220│Polarized scattering│ 363│ 331│ 179│ 1.23 │
│ │ │Film│ │ │ │ │
│Comparative Example 2-5│ 140│Diffusion film│ 126│ 422│ 194│ 1.34 │
│ │ │Lum │ │ │ │ │
└──────┴────┴────┴────┴┴────┴────┴───┘

  As is clear from the above results, the organic EL elements of Examples 2-1 and 2-2 of the present invention had a front luminance before the polarization scattering film was bonded, for example, compared to the organic EL element of Reference Example 2-2. Although it is small, the front brightness greatly increases after the polarization scattering film is bonded, and when the front brightness after installing the polarizing plate is seen, the output light is rich in linearly polarized light. Therefore, it can be seen that the absorption at the polarizing plate is small, and the final decrease in luminance is minimized.

  In contrast, in the organic EL element of Comparative Example 2-5, the front luminance after the formation of the light diffusion layer was higher than that of the organic EL element of Example 2-1, but the emitted light was polarized. Since it is natural light that is not generated, more than half of the light is absorbed by the polarizing plate, and finally the front luminance is lower than that of the organic EL element of Example 2-1. In addition, in the organic EL elements of Comparative Examples 2-1 to 4, the luminance improvement degree after forming the light diffusion layer was small, and the final luminance was lower than that of the organic EL element of Example 2-1. It was.

Example 2-3
In Example 1-5, instead of forming a light diffusing layer by laminating 10 diffusive adhesives on the surface of a glass substrate of an organic EL element as a basic structure, the polarization formed in Example 2-1 The organic EL element was produced by bonding the film as a scattering part together through an acrylic adhesive.
Next, after setting the polarizing plate on the polarization scattering portion of the organic EL element so that the extending direction of the polarization scattering portion of the organic EL element thus produced and the transmission axis of the polarizing plate are parallel, When a voltage of 21 V was applied to drive the device at a current density of 20 mA / cm ² and the front luminance was measured, a luminance of 229 cd / m ² was obtained.

Comparative Example 2-6
In Comparative Example 1-6, instead of forming a light diffusing layer by laminating 10 diffusive adhesives on the surface of the glass substrate of the organic EL device as the basic structure produced, the polarization formed in Example 2-1 The organic EL element was produced by bonding the film as a scattering part together through an acrylic adhesive.
Next, after placing the polarizing plate on the polarization scattering portion of the organic EL element so that the extending direction of the polarization scattering portion of the organic EL element thus produced and the transmission axis of the polarizing plate are parallel, When a voltage of 12.7 V was applied and the device was driven at a current density of 20 mA / cm ² to measure the front luminance, a luminance of 158 cd / m ² was obtained.

When the above Example 2-3 and Comparative Example 2-6 were compared, the luminance obtained with the same element current was improved by about 1.4 times. When the same polarizing plate is installed in the element of Example 1-5, the front luminance decreases from 351 cd / m ² to 161 cd / m ² due to absorption of the polarizing plate, but the polarized light scattering site of the present invention is added to the diffusion layer. By using it, the guided light can be extracted as linearly polarized rich light. Therefore, when used as a backlight for a liquid crystal display device, the efficiency can be further increased by 1.4 times. That is, when used as a backlight light source for a liquid crystal display device, when the effect of enhancing and extracting the guided light according to the present invention is combined with the effect of emitting polarized light, the brightness can be increased by a factor of about 2 compared to the prior art. Was confirmed.
Note that, when applied to a backlight for a liquid crystal display device, even if a reflective polarizer is provided, absorption by the polarizing plate can be reduced, whereby luminance can be increased. This is also clear from the results of Example 3 below.

  Next, in the organic EL element of the present invention, “Examples 3-1 to 4” in which a light diffusive adhesive is provided as a region that causes disturbance in the reflection / refraction angle and a reflective polarizer is provided are described. In contrast to this and “Comparative Examples 3-1 to 10”, the present invention will be specifically described.

Example 3-1
In the same manner as in Example 1-1, the thickness of the electron transporting light emitting layer [Alq represented by the formula (5)] is 140 nm, and the relationship of the formulas (1) and (2) of the present invention is satisfied. Then, an organic EL element was formed before forming a region in which the reflection / refraction angle was disturbed.
Next, on the glass substrate of the organic EL element as the basic structure, 10 light diffusing pressure-sensitive adhesives formed by the following method are laminated and pasted as a region in which the reflection / refraction angle is disturbed. A light diffusion layer having a thickness of approximately 200 μm was formed. Further, a reflective polarizer formed by the following method was bonded onto this light diffusion layer to produce an organic EL element.

<Formation of light diffusing adhesive>
To 10 g of toluene, 1.5 g of silicone particles having a refractive index of 1.43 and a particle diameter of 4 μm was added and stirred well. Further, an acrylic pressure-sensitive adhesive having a refractive index of 1.47 was dissolved in toluene so that the concentration was 20% by weight. This solution is added to the toluene solution in which the silicone particles are dispersed so that the silicone concentration with respect to the adhesive is 15% by weight, and the concentration is adjusted so that the concentration of the adhesive with respect to toluene is 20% by weight. And stirred well. Using the applicator, the prepared solution was applied onto the separator and dried to prepare a 20 μm thick light-diffusing adhesive.

<Formation of reflective polarizer>
A polyvinyl alcohol layer having a thickness of 0.1 μm is provided on a cellulose triacetate film having a thickness of 50 μm that does not exhibit birefringence, and an alignment film is formed by rubbing with a rayon cloth. A 20% by weight tetrahydrofuran solution of an acrylic thermotropic cholesteric liquid crystal polymer is applied with a wire bar, dried, heated and treated at 150 ± 2 ° C. for 5 minutes, allowed to cool to room temperature, and 1 μm thick. Depending on the method of forming the cholesteric liquid crystal polymer layer, the wavelength range showing circular dichroism is (A) 350 to 450 nm, (B) 450 to 550 nm, (C) 600 to 700 nm, (d) 750 to 850 nm, Four cholesteric liquid crystal polymer layers that specularly reflect circularly polarized light were obtained.
Next, the above cholesteric liquid crystal polymer layers (A) and (B) are subjected to thermocompression treatment at 150 ± 2 ° C. for 2 minutes after the liquid crystal surfaces are adhered to each other, and then the cellulose triacetate on the (B) side. The film was peeled off, and the cholesteric liquid crystal polymer layer (C) was adhered to the exposed surface of the liquid crystal polymer layer, and the liquid crystal surfaces were brought into close contact with each other and subjected to thermocompression bonding at 150 ± 2 ° C. for 2 minutes. Further, according to the above, the cholesteric liquid crystal polymer layer of (D) is also subjected to thermocompression treatment to change the helical pitch in the thickness direction and exhibit a circular dichroism from a cholesteric liquid crystal layer having a wavelength range of 400 to 800 nm. A reflective polarizer is obtained.

Example 3-2
In the same manner as in Example 1-2, the thickness of the electron transporting light emitting layer [Alq represented by the formula (5)] is 120 nm, and the relationship of the formulas (1) and (2) of the present invention is satisfied. Then, an organic EL element was formed before forming a region in which the reflection / refraction angle was disturbed.
Next, a light diffusion layer having a thickness of approximately 200 μm is formed on the glass substrate of the organic EL element as the basic configuration as a region that causes disturbance in the reflection / refraction angle in the same manner as in Example 3-1. did. Further, a reflective polarizer was bonded onto the light diffusion layer in the same manner as in Example 3-1, to produce an organic EL element.

Comparative Example 3-1
As the electron-transporting light-emitting layer, a region that causes disturbance in the reflection / refraction angle is formed in the same manner as in Example 1-1 except that Alq represented by Formula (5) is formed to a thickness of 65 nm. The previous organic EL element was produced. A voltage of 8.8 V was applied to the device, current was passed through the device at a current density of 10.5 mA / cm ² , and light was emitted. Evaluation was performed in the same manner as in Example 1-1. The results are as follows: 0 °: 314 cd / m ² , 10 °: 315 cd / m ² , 20 °: 312 cd / m ² , 30 °: 309 cd / m ² , 40 °: 298 cd / m ² , 50 °: 285 cd / m ² 60 °: 274 cd / m ² , 70 °: 257 cd / m ² , and 80 °: 229 cd / m ² .

From this result, the luminance distribution as the basic configuration before forming the region that causes the disturbance of the reflection / refraction angle does not satisfy the relationship of the formula (1) of the present invention, and the value of the Alq layer of 65 nm is The relationship of the formula (2) of the invention was not satisfied.
Next, a light diffusion layer having a thickness of approximately 200 μm is formed on the glass substrate of the organic EL element as the basic configuration as a region that causes disturbance in the reflection / refraction angle in the same manner as in Example 3-1. did. Further, a reflective polarizer was bonded onto the light diffusion layer in the same manner as in Example 3-1, to produce an organic EL element.

Comparative Example 3-2
In the same manner as in Comparative Example 1-2, the thickness of the electron-transporting light-emitting layer [Alq represented by Formula (5)] is 25 nm, and the relationship of Formula (1) and Formula (2) of the present invention is satisfied. The organic EL element before forming the area | region which produces disorder in a reflection and a refraction angle was produced.
Next, a light diffusion layer having a thickness of approximately 200 μm is formed on the glass substrate of the organic EL element as the basic configuration as a region that causes disturbance in the reflection / refraction angle in the same manner as in Example 3-1. did. Further, a reflective polarizer was bonded onto the light diffusion layer in the same manner as in Example 3-1, to produce an organic EL element.

Comparative Example 3-3
In the same manner as in Comparative Example 1-3, the thickness of the electron-transporting light-emitting layer [Alq represented by Formula (5)] is 180 nm, and the relationship of Formulas (1) and (2) of the present invention is satisfied. The organic EL element before forming the area | region which produces disturbance in a reflection and a refraction angle was produced.
Next, a light diffusion layer having a thickness of approximately 200 μm is formed on the glass substrate of the organic EL element as the basic configuration as a region that causes disturbance in the reflection / refraction angle in the same manner as in Example 3-1. did. Further, a reflective polarizer was bonded onto the light diffusion layer in the same manner as in Example 3-1, to produce an organic EL element.

Comparative Example 3-4
In the same manner as in Comparative Example 1-4, the electron transporting light emitting layer [Alq represented by Formula (5)] has a thickness of 220 nm and satisfies the relationship of Formulas (1) and (2) of the present invention. The organic EL element before forming the area | region which produces disturbance in a reflection and a refraction angle was produced.
Next, a light diffusion layer having a thickness of approximately 200 μm is formed on the glass substrate of the organic EL element as the basic configuration as a region that causes disturbance in the reflection / refraction angle in the same manner as in Example 3-1. did. Further, a reflective polarizer was bonded onto the light diffusion layer in the same manner as in Example 3-1, to produce an organic EL element.

  About each organic EL element of said Examples 3-1 and 2 and Comparative Examples 3-1-4, the case where it uses as a backlight for liquid crystal display devices was assumed, and the performance test was done by the following method. The results were as shown in Table 3-1.

<Performance test of organic EL element>
“NPF-HEG1425DU” manufactured by Nitto Denko Corporation was used as an absorption type polarizing plate. The thickness was 180 μm. As a ¼ wavelength plate (λ / 4 wavelength plate), a norbornene resin film (“Arton” manufactured by JSR) was stretched 1.5 times at 180 ° C. (longitudinal uniaxial stretching), and a wavelength λ = 550 nm. It adjusted so that it might be set to (DELTA) nd = 135nm. The thickness was 90 μm.
The absorption axis of the absorptive polarizing plate and the stretching axis of the quarter-wave plate were bonded with an acrylic pressure-sensitive adhesive so that the angle formed was 45 °.
The polarizing plate with a quarter wavelength plate obtained in this way is placed on the light emitting surface of each organic EL element, and a predetermined voltage is applied to each element so that a current of 10.5 mA can be passed. Luminance was measured. In addition, the luminous efficiency (cd / A) was examined.

Table 3-1.
┌──────┬┬──────┬───────┬┬───────┬──────┐
│ │Alq layer │ Current density │ Front brightness │ Luminous efficiency │
│ │Film thickness (nm) │ (mA / cm ² ) │ (cd / m ² ) │ (cd / A) │
├──────┼┼──────┼───────┼┼───────┼──────┤
│Example 3-1│ 140 │ 10.5 │ 323 │ 3.08 │
│Example 3-2│ 120 │ 10.5 │ 337 │ 3.21 │
├──────┼┼──────┼───────┼┼───────┼──────┤
│Comparative Example 3-1│ 65 │ 10.5 │ 235 │ 2.24 │
│Comparative Example 3-2│ 25 │ 10.5 │ 73 │ 0.70 │
│Comparative Example 3-3│ 180 │ 10.5 │ 156 │ 1.49 │
│Comparative Example 3-4│ 220 │ 10.5 │ 216 │ 2.06 │
└──────┴┴──────┴───────┴┴───────┴──────┘

  As is clear from the results of Table 3-1 above, the organic EL elements of Examples 3-1 and 2 of the present invention are both higher in front luminance than any of the organic EL elements of Comparative Examples 3-1 to 4. As can be seen from the graph, the luminous efficiency is very good.

Comparative Example 3-5
An organic EL device was produced in the same manner as in Example 3-1, except that neither the light diffusion layer nor the reflective polarizer was formed. That is, this organic EL element is the organic EL element itself as a basic configuration in Example 3-1.

Comparative Example 3-6
An organic EL element was produced in the same manner as in Example 3-1, except that only the light diffusion layer was formed and no reflective polarizer was formed.

Comparative Example 3-7
An organic EL element was produced in the same manner as in Example 3-1, except that the light diffusion layer was not formed and only the reflective polarizer was formed.

Comparative Example 3-8
An organic EL element was produced in the same manner as Comparative Example 3-1, except that neither the light diffusion layer nor the reflective polarizer was formed. That is, this organic EL element is the organic EL element itself as a basic configuration in Comparative Example 3-1.

Comparative Example 3-9
An organic EL element was produced in the same manner as in Comparative Example 3-1, except that only the light diffusion layer was formed and no reflective polarizer was formed.

Comparative Example 3-10
An organic EL device was produced in the same manner as in Comparative Example 3-1, except that only the reflective polarizer was formed without forming the light diffusion layer.

  About each organic EL element of said Comparative Examples 3-5-7 and Comparative Examples 3-8-10, the case where it used as a backlight for liquid crystal display devices was assumed, and the performance test was done similarly to the above. These results are shown in Table 3-2 together with the results of Example 3-1 corresponding to Comparative Examples 3-5 to 7 and the results of Comparative Example 3-1 corresponding to Comparative Examples 3-8 to 10. It was.

Table 3-2
┌──────┬────┬─────┬───┬───┬─────┬────┐
│ │Alq layer │Current density │Light diffusion │Reflective │Front brightness │Luminescence efficiency│
│ │ Film thickness │ │ Layer │ Polarizer │ │ │
│ │ (nm) │ (mA / cm ² ) │ Presence │ Presence │ (cd / m ² ) │ (cd / A) │
├──────┼────┼─────┼───┼───┼─────┼────┤
│Example 3-1│ 140│ 10.5│ Yes│ Yes│ 323│3.08│
│Comparative Example 3-5│ 140│ 10.5│ None│ None│ 68│0.65│
│Comparative Example 3-6│ 140│ 10.5│ Yes│ No│ 215│2.05│
│Comparative Example 3-7│ 140│ 10.5│ None│ Available│ 113│1.08│
├──────┼────┼─────┼───┼───┼─────┼────┤
│Comparative Example 3-1│ 65│ 10.5│ Yes│ Yes│ 235│2.24│
│Comparative Example 3-8│ 65│ 10.5│ None│ None│ 142│1.36│
│Comparative Example 3-9│ 65│ 10.5│ Yes│ No│ 168│1.60│
│Comparative Example 3-10│ 65│ 10.5│ None│ Available│ 231│2.20│
└──────┴────┴─────┴───┴───┴─────┴────┘

From the results of Table 3-2 above, in the normal organic EL elements of Comparative Examples 3-5 and 8 in which neither the light diffusion layer nor the reflective polarizer is formed, the expressions (1) and (2) The luminous efficiency is higher in Comparative Example 3-8, which is not satisfactory, but the above tendency is reversed between the organic EL elements of Comparative Examples 3-6 and 9 in which only the light diffusion layer is formed. The luminous efficiency is higher in Comparative Example 3-6 that satisfies 1) and Equation (2).
This is because the configuration of the organic EL element is determined so as to intensify guided light that is not normally extracted, which is an effect of the present invention. That is, by forming the light diffusion layer, the guided light is extracted, and as a result, the light emission efficiency is increased. Thus, Example 3-1 which formed the reflection type polarizer further in the organic EL element of comparative example 3-6 which raised luminous efficiency in this way has much higher luminous efficiency compared with said comparative example 3-6. Become.

In addition, the organic EL elements of Comparative Examples 3-7 and 3-10, in which only the reflective polarizer is formed, are organic of Comparative Examples 3-5 and 3-8, respectively, due to the action of the reflective polarizer. The luminous efficiency is about 1.6 times higher than that of the EL element. However, compared with the organic EL element of Example 3-1, the value was still small.
From the above test results, it was confirmed that the organic EL element of the present invention was excellent as a polarization plane light source for a liquid crystal display device.

Example 3-3
For an organic EL element in which an optical compensation layer is further bonded to the surface of the reflective polarizer via an acrylic transparent adhesive, a performance test as a backlight for a liquid crystal display device is performed in the same manner as described above. went. However, here, a voltage was applied so that a current of 10.5 mA was passed, and luminance values of 0 to 80 degrees in front were measured every 10 degrees. The results are shown in FIG. 11 together with the similar test results for the organic EL element of Example 3-1.
In the figure, curve -c is Example 3-1, and curve -d is Example 3-3. The used optical compensation layer was prepared by the following method.

<Preparation of optical compensation layer>
The side chain type liquid crystal polymer represented by the following formula (11) (wherein n = 35 represents the mol% of the monomer unit, and the block body is indicated for convenience. The weight average molecular weight is 5,000. ) A solution obtained by dissolving 25 parts by weight in 75 parts by weight of cyclohexanone was applied by spin coating onto a plastic film having a thickness of 20 μm using a norbornene polymer (“Zeonex” manufactured by Nippon Zeon Co., Ltd.) as a polymer material. did.
Next, after heating at 130 ° C. for 1 minute, it is cooled to room temperature at once, the liquid crystal layer is homeotropically aligned, and the homeotropic alignment liquid crystal layer is fixed while maintaining the alignment, and the in-plane refractive index is constant. An optical compensation layer having a large refractive index in the thickness direction was produced.

As is clear from FIG. 11, in the organic EL element of Example 3-1, the luminance tends to decrease as the angle becomes wider. However, in the organic EL element of Example 3-3, an optical compensation layer is inserted. Thus, it can be seen that high luminance is obtained in a wide angle range.
In addition, although the angle distribution of Examples 3-1 and 3 does not satisfy Formula (1), this shows the measurement result after forming the area | region which produces disorder in the reflection and refraction angle of light. Because it is. Needless to say, in the present invention, the basic configuration of the organic EL element is determined so as to satisfy the formula (1) in a state before forming a region in which the reflection / refraction angle of light is disturbed.

Example 3-4
An organic EL device in the same manner as in Example 3-1, except that “DBEF” manufactured by 3M was used as a reflective linear polarizer instead of a reflective circular polarizer composed of a cholesteric liquid crystal layer. Was made.
About this organic EL element, the performance test as a backlight for liquid crystal display devices was performed. That is, “NPF-HEG1425DU” manufactured by Nitto Denko Corporation is used as an absorption type polarizing plate, and this polarizing plate is placed on the DBEF of the element so as to maximize the transmittance so that a current of 10.5 mA can be passed. A voltage was applied to measure the front luminance.
As a result, a value of 308 cd / m ² was obtained, and it was confirmed that the same effect as in Example 3-1 was achieved.

It is sectional drawing which shows the 1st example of the organic electroluminescent element of this invention. It is a characteristic view (before forming the area | region which produces disorder in a reflection and a refraction angle) about the basic composition of this invention and the conventional organic electroluminescent element. It is sectional drawing which shows the 2nd example of the organic electroluminescent element of this invention. It is sectional drawing which shows the 3rd example of the organic electroluminescent element of this invention. It is sectional drawing which shows the 4th example of the organic electroluminescent element of this invention. It is sectional drawing which shows the 5th example of the organic electroluminescent element of this invention. It is sectional drawing which shows the 6th example of the organic electroluminescent element of this invention. It is sectional drawing which shows the example which applied the organic electroluminescent element of this invention to the liquid crystal display device. It is principle explanatory drawing of the organic electroluminescent element of this invention. It is explanatory drawing of the characteristic of the organic electroluminescent element of Example 1-1. It is a characteristic view regarding the brightness | luminance of the organic electroluminescent element of Example 3-1 and Example 3-3. It is explanatory drawing which shows the light emission area | region of an organic electroluminescent element. It is explanatory drawing about the brightness | luminance of an organic electroluminescent element.

Explanation of symbols

1 Support substrate (glass substrate)
2 Transparent electrode (anode)
3 Reflective electrode (cathode)
DESCRIPTION OF SYMBOLS 4 Hole transport layer 5 Electron transport light emitting layer 6 Light emission area | region 7 Area | region which produces disorder in reflection and a refraction angle 70 Polarized light scattering part 8 Reflective polarizer 9 1/4 wavelength plate 10 Polarizing plate 11 Liquid crystal cell

Claims (16)

A pair of electrodes composed of at least one organic layer including a light emitting layer and an anode electrode and a cathode electrode, at least one of which is a transparent electrode sandwiching the organic layer, is a front surface of the emitted light emitted from the light extraction surface to the observer side. In the organic electroluminescence device formed so that the luminance value and the luminance value in the direction of 50 ° to 70 ° satisfy the relationship of the formula (1); the front luminance value <the luminance value in the direction of 50 ° to 70 °. The region where the reflection / refraction angle of light is disturbed until the light is emitted from the light emitting layer to the observer side through the transparent electrode is provided substantially without the air layer. An organic electroluminescence device characterized. One of the anode electrode and the cathode electrode is a transparent electrode, and the other is a reflective electrode. The distance between the substantially central portion of the recombination light-emitting region of holes and electrons and the reflective electrode is d (nm), and light emission When the peak wavelength of the fluorescence emission spectrum of the material used for the layer is λ (nm) and the refractive index of the organic layer between the light emitting layer and the reflective electrode is n, formula (2); (0.3 / n The organic electroluminescence device according to claim 1, satisfying a relationship: λ <d <(0.5 / n) λ. 3. The organic material according to claim 1, wherein the region in which the reflection / refraction angle of light is disturbed includes a light diffusing portion in which a transparent material or an opaque material having a different refractive index is dispersed and distributed in the transparent material. Electroluminescence element. The organic electroluminescence device according to claim 1, wherein the region in which the reflection / refraction angle of light is disturbed has a lens structure. The organic electroluminescence element according to claim 1, wherein the region in which the reflection / refraction angle of light is disturbed is an uneven surface. The organic electroluminescence device according to any one of claims 3 to 5, further comprising a reflective polarizer closer to the observer side than a region in which the reflection / refraction angle of light is disturbed. The organic electroluminescence device according to claim 6, wherein the reflective polarizer is a reflective circular polarizer composed of a cholesteric liquid crystal layer. The organic electroluminescence device according to claim 6, wherein the reflective polarizer is a reflective linear polarizer obtained by laminating at least two kinds of materials having different refractive indexes. The organic electroluminescence according to any one of claims 6 to 8, wherein an optical compensation layer having no refractive index anisotropy in the plane and having a refractive index in the thickness direction larger than the in-plane refractive index is provided. element. 3. The organic electroluminescence according to claim 1, wherein the region in which the reflection / refraction angle of light is disturbed comprises a polarization-scattering portion in which micro regions having different birefringence characteristics are dispersed and distributed in the translucent resin. element. The micro region in the polarized light scattering region is composed of either a liquid crystalline material, a glass state material in which a liquid crystal phase is supercooled and fixed, or a material in which a liquid crystal phase of a polymerizable liquid crystal is cross-linked and fixed by energy rays. The organic electroluminescent element of description. The polarization-scattering part is formed by dispersing and containing in a translucent resin a microregion made of a liquid crystal polymer having a glass transition temperature of 50 ° C. or higher that exhibits a nematic liquid crystal phase at a temperature lower than the glass transition temperature of the resin. The organic electroluminescent element of description. The polarized light scattering part is between the minute region and the other portion in the axial direction (Δn ₁ direction) in which the refractive index differences Δn ₁ , Δn ₂ , Δn ₃ in the minute region are maximum. 0.03 to 0.5 ([Delta] n ₁₎ a and, two axial directions ([Delta] n ₂ direction, [Delta] n ₃ direction) perpendicular to the axial direction of any of claims 10 to 12 is 0.03 or less in Organic electroluminescence device. A surface light source comprising the organic electroluminescence element according to claim 1. A polarization plane light source comprising the organic electroluminescence device according to claim 6. A display device comprising the surface light source according to claim 14 or the polarization surface light source according to claim 15.

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